Objective: We aimed to determine sleep quality of medical faculty assistants and evaluate this with socio-demographic characteristics. Method: This cross-sectional study was conducted from June to October 2012, after receiving approval from local Ethics Committee. The data for the research were collected using the Pittsburgh Sleep Quality Index (PSQI) and a socio-demographic questionnaire completed with face-to-face interviews after providing necessary explanation and receiving oral consent of the participants. Results: A total of 133 residents were included in the study. Significant differences were found between their bedtimes, time to falling asleep, duration of sleep and waking time with mean PSQI scores for residents included in the study according to their clinical departments (p<0.05). According to departments, the highest PSQI scores and worst sleep quality were observed among residents working in surgical departments and anesthesiology (24.7±7.8; p<0,05). Conclusion: As highest PSQI scores and worst sleep quality were obtained by anesthesiology residents, we have concluded that precautions must be taken for the safety of patients and health workers in surgical departments and intensive care units.