Depression is one of the most common complications in patients with chronic somatic illnesses. Comorbidity of depression with physical illness often remains unrecognized and untreated, additionally aggravating the somatic illness itself, its treatment and prognosis. The aim of this study was to investigate the prevalence of depression in chronic somatic patients suffering from diabetes, epilepsy, asthma, chronic obstructive pulmonary disease (COPD) and hypothyroidism. Patients, who were regularly attending control examinations in neurological and internal medicine out-patient departments, were tested for the presence of depression with Beck Depression Inventory. The sample comprised 2153 chronic somatic patients aged between 18 and 80 years. Out of this total, 228 patients (10.6%) did not complete the study, (5.12%) refused to participate, and (5.5%) of the patients were technical failures. 1925 patients completed the study, and 1383 of them were not depressive. In 542 patients (28.5%) depression was confirmed, being almost twice more frequent in women, 346 (64%) vs. 196 (36%) male. Among these depressed examinees, mild depression was found in 284 (52.4%), major in 186 (34.3%) and severe in 72 (13.3%) chronic somatic patients. The majority of patients were aged over 55 yrs (49%). This population contained the largest number of depressed examinees (49.9%). The prevalence of depression with regard to subgroups shows that (25.6%) of asthma patients were depressed, as well as (26.6%) of those with COPD. These two groups did not present statistically significant differences regarding gender. The depression level of (32.2%) was found in patients with diabetes, of (29.6%) in patients with epilepsy and of (24.2%) among those with hypothyroidism. As for gender, statistically significant difference was found in the last three groups of patients (p < 0.001).