Objective. Over the last 30 years, the issue of the relationship of satisfaction of patient care to compliance is becoming increasingly acute in the world. Numerous studies around the world have shown that it is the satisfaction of patient with inpatient care that correlates positively with the compliance and disease outcomes in the field of psychiatry, as well as in any medical sector as a whole and is one of the most important elements of treatment. The Action Plan 2013-2020 developed by the Ministry of Health of Latvia, in line with the initiative announced by the WHO in health care, has mentioned that one of the priorities in promoting health is by improving the quality of available health care, especially in the field of mental health care (World Health Organization, 2015), which emphasizes the importance of the doctoral thesis studying patients' satisfaction with treatment in mental health care hospital. The aim of the work was to evaluate the relationship between satisfaction and such factors as compliance indirect measures and re-hospitalisation rates of patients with schizophrenia spectrum disorders, affective and neurotic spectrum disorders. Material and methods. A cross-sectional study was conducted from 1 January 2018 to 1 December 2018 in patients with mental disorders who have been hospitalised in acute or subacute hospital units. The study tool was an adapted two-language questionnaire for self-assessment of patients' satisfaction of treatment. A total number of 1335 respondents have been analysed in the doctoral thesis work. The respondent rate was 62% (n=823). In statistical data processing, there the following methods were used: descriptive statistics for the respondents and non-respondents' groups, t-test or Welch test for comparing continuous variables, Chi-square test for comparing two categorical variables, linear regression for the relationship between socio-demographic factors with compliance undirect measures and Spearman correlation coefficient for the relationship between different indicators in diagnostic groups, satisfaction in questionnaire scales and surrogate ratios of compliance. Results. Respondents were elderly patients (p<0,001), women, with higher or secondary education (p<0,001), more often unemployed, with a status of disabled or retired (p<0.001), with relationship experience (p<0,001), more frequent with schizophrenia and affective spectrum disorders (p<0.001) with somatic co-diagnosis (p<0.001) and previous experience in mental health care (p<0.001). When compiling results for higher or lower satisfaction with treatment, older patients (p<0.001), women (p=0.003) with higher, secondary, and professional education (p=0.001), employees, patients with a disability or pensioner status (p<0,001), with relationship history (married, divorced, widowed) (p<0,001), patients with affective spectrum disorders and organic mental disorders (p<0,001), patients with somatic side diagnosis (p-0,010) were more satisfied in PIPEQ-OS questionnaire. Patients who scored treatment higher were more likely to take the medicine after discharge from inpatient (p<0.001). Age positively correlated with satisfaction in the interaction with patient (B 0.08, p=0.001) and in the structure and facility scale (B 0.10, p<0.001), lower education was positively correlated with satisfaction in the interaction with patient scale (B 0.569, p=0.003), the unemployed status negatively correlated with satisfaction in the outcomes scale (B -0.191, p=0.009). PIPEQ-OS questionnaire all three scales were identified for poor correlation of satisfaction with the number of subsequent outpatient visits in patients with affective spectrum disorders. In patients with affective spectrum disorders and schizophrenia spectrum disorders, a positive correlation was observed between satisfaction with interaction scale (rs 0.207, p=0.010; rs 0.151, p=0.000 as appropriate) and structure and facilities scale (rs 0.236, p=0.000; rs 0.184, p=0.001 as appropriate) and frequency of medication use. It was established that 3 questionnaire scales (interaction scale (rs -0.074, p=0.034), structure and facilities scale (rs -0.081, p=0.021) and outcome scale (rs -0.102, p=0.004) negatively correlated with the subsequent frequency of outpatient visits. A positive correlation was established for all questionnaire scales (interactions (rs 0.174, p<0.001), structure (rs 0.086, p<0.001) and outcomes (rs 0.073, p=0.039)) and further medication use. Conclusions. In the research work, we identified factors related to patients' satisfaction with treatment as well as we detected patients' satisfaction correlation with further outpatients visits and medication use. Higher satisfaction was detected among older age patients, women, those with professional and middle education, working, disabled or retired, patients with relationship history. The lowest score had questions about family involvement, possibilities to influence the treatment and provided information. Lowest satisfaction was among schizophrenia and neurotic and stress-related disorders. Higher satisfaction correlated with medication use. PIPEQ-OS can be used in inpatient mental health care to measure patients’ satisfaction with received care. Our findings could be used for improvements in the treatment process in inpatient care facilities and promoting personal to engage more in the care of patients. Our results could help to improve compliance in patients with different diagnoses and influence the treatment outcomes and patients' adjustment to their disorder.