Depression is a common symptom in cancer patients, which is difficult to be detected and consequently to be treated. It deteriorates over the the course of cancer treatment, persists long after the end of therapy and influences negatively the quality of life . Aim: The purpose of the present study was to evaluate the levels of depression that experience patients undergoing chemotherapy. Method and material: The sample study included 159 patients with cancer, who received chemotherapy in one day-clinic department. Data was collected by using the self-completed questionnaire «Zung Self Rating Depression Scale» (SDS). Statistical analysis was carried out using t-test, Anova and SPSS-15. Results: From the 159 patients studied, percentage of 34% was men and 66% women. According to the level of depression, 67,7% experienced normal levels of depression, 21,5% mild, 10,2% moderate and 0,6% severe depression. The statistical analysis showed that patients >70 years old experienced higher levels of depression, compared to those of <50 and 51-60 years old, p=0,025 and p=0,005, respectively. In regard to the occupation, it was found that, pensioners experienced higher levels of depression compared to employees, public or private and free lancers, p=0,014 and p=0,018 respectively, while, they didn’t differ statistically significant from those of domestic duties, p=0,765. In regard to the educational status, patients of primary education experienced higher level of depression compared to those of secondary and higher/university education, p=<0,001 and p=0,012 respectively. Patients who received chemotherapy but with no response experienced higher levels of depression compared to those who received adjuvant chemotherapy, p=0,050. Patients who received antidepressant or hypnagogic medication experienced higher levels of depression compared to those who were not under medication or received symptomatic-alleviative medication p=<0,001 and p=0,001 respectively. Similarly, higher levels of depression experienced patients who were not nourished adequately, p=<0,001, as well as those who had a co-existing disease, p=0,029. Conclusions: Health professionals should be fully informed about depression and its dimensions. Early diagnosis of depression consists a matter of great importance for a medical treatment and planning of care based mainly on the personal needs of each individual.