To explore structure and process factors which influence patients' perception of quality inpatient psychiatric nursing care at Mathari hospital. This was a cross-sectional study of 236 inpatients selected by stratified random sampling. Competence to give consent was determined by a minimum score of 24 on Mini Mental State Examination. Patients were interviewed using a semi-structured questionnaire. Differences in proportions of variables were determined by calculating confidence interval and summary chi-squared statistics. P-values of < or =0.05 were considered significant. Majority of patients (87%) were aged 20-49 years with 43% having stayed in the ward for over a month. Structure factors related to patients' perception of care included physical environment, being happy with the way the ward looked was significantly related to satisfaction with care (chi(2) = 5.506, P = 0002). Process factors significantly related to patients' satisfaction with care included nurses providing patients with information on prescribed medicines (chi(2) = 10.50, P = 00012). Satisfaction with care was positively related to ability to recommend someone for admission in the same ward (chi(2) = 20.2, P = 00001). Structure and process factors identified as influencing patients' perception of care were physical environment and nurses' qualities that fit within the characteristics of Peplau's Interpersonal Relations Theory.