OBJECTIVE Prevalence rates of mental health problems in primary care vary according to population and the type of measure used. This study examined the prevalence of a full range of mental health problems, including sub-threshold diagnoses, and the socio-demographic risk factors for psychiatric disorders among a population with low out-of-pocket expenditures for medical care. METHODS Four validated mental health assessment instruments, including the CIDI-SF, were administered to a sample of 976 users of primary care in Israel between the ages of 25-75 in eight clinics throughout the country. Prevalence estimates were obtained for seven psychiatric diagnoses, two "other mental health disorders" (somatization and disordered eating) and five sub-threshold conditions. RESULTS The most common types of morbidity were depression and disordered eating (20.6% and 15.0%, respectively), followed by somatization (11.8%) and general anxiety (11.2%). Among respondents, 31.1% had at least one psychiatric diagnosis, 24.3% had 'other mental disorders' and 15.5% had sub-threshold conditions. Panic attack, disordered eating and somatization, as well as a global measure of any psychiatric diagnosis were significantly more prevalent among women than men. Psychiatric diagnoses were also more common among those in the age group 45-64, with less education and insufficient income, the never married and separated/divorced and those not working. No significant differences were found between recent immigrants, veteran immigrants and Israeli-born, between Arab and Jewish Israelis or between secular or religious sectors of the population. CONCLUSIONS This study establishes the prevalence of the most common disorders in primary care including PTSD, somatization and disordered eating behaviors. The additional of other mental disorders suggests that a more accurate picture of mental disorders in primary care requires an expanded assessment procedure.