Introduction The aim of the present study was to determine the prevalence of somatization, anxiety, depression and stress in a primary care population, explore their association to psychosocial stressors and determine the diagnostic overlap of these four mental disorders. Methods This is a prospective cross-sectional study. A representative sample of 2,150 patients was approached, of whom 1,762 patients agreed to participate and responded to the questionnaire (81.9%). Anxiety was assessed with the Generalized Anxiety Disorder Scale (GAD-7). Depression was assessed with the depression module Patients Health Questionnaire-8. Somatization was measured with the somatic symptom module PHQ-15. The Perceived Stress Scale (PSS) instrument was used to identify the stress cases. Results Of the study sample, 23.8% of the total cases were identified as probable cases. The prevalence of somatization, depression, anxiety and stress was 11.7%, 11.3%, 8.3% and 18.6%, respectively. The specific gender prevalence of these four psychological disorders was very similar in men and women: depression (11.3% versus 11.3%), anxiety (7.7% versus 8.9%), somatization (12.5% versus 10.7%) and stress disorders (19.3% versus 17.8%). A significant difference was observed in nationality and marital status for depression and anxiety (P<0.05). The age-specific prevalence rate showed a higher prevalence in the age group 4554 years: depression (13.3%), anxiety (9.5%), somatization (12.8%) and stress (20.4%). Unable to control worries (69.2%) was the worst symptom for anxiety disorders, while the majority of the depressed patients wanted to hurt themselves (71.9%). Stomach pain (46.1%) was the most common symptom in somatic patients. Most of the patients experiencing stress could not cope with their daily duties (65.9%). There was a high comorbidity rate of depression, anxiety, somatization and stress observed in the studied population (9.3%). Conclusion The prevalence of somatization and depression was similar, but the prevalence of stress was higher in inpatient patients. Somatization, depression, anxiety and stress disorders co-occurred at higher rate in the study sample.