Objectives: The objective of this study was to determine the incidence of somatic diseases in patients diagnosed with depression, to determine the relation between depression and somatic diseases as well as to evaluate if observed diseases are independent risk factors for depression and vice versa. Finally, the aim was to determine the significance of correlation between depression and somatic diseases for treatment outcomes. Study design: The study was structured as a cross-sectional study. Respondents and methods: Respondents included in the study are patients diagnosed with depression between 20 and 70 years of age. The respondents were treated at the Clinic for Psychiatry of Clinical Hospital Centre Osijek between 1st of January and 31st of December 2016. As the source data, we used medical records of respondents diagnosed with depression. Results: The study involved 115 respondents diagnosed with depression, 49,6 % of whom were men, and 50,4 % women. 82,6 % of the respondents had coexisting somatic diseases, found significantly more frequently in women, while 65,2 % of respondents had coexisting mental diseases, found significantly more frequently in men. Most common coexisting somatic disease was hypertension, 49 % of respondents. 2,6 % of the respondents suffered complications (side effects of the treatment) during the treatment. Considering the treatment outcome, most of the respondents (87 %) achieved complete clinical remission, while 13 % of the respondents achieved partial remission. Conclusion: The study indicated high positive correlation between depression and somatic diseases. Comorbidity, mental disease heredity, previous diseases and risk factors do not reveal statistically significant differences between groups of respondents who achieved complete clinical remission and those who achieved only partial remission. The respondents with complications during the treatment significantly more frequently achieved only partial remission, which demands regular outpatient treatment.