ABSTRACT Aim: This study was a descriptive analysis aimed to determine effects of intensive unit care environment on patient’s sleep taken medical treatment in the cardiology intensive care unit. Method: This study have been done with 40 patients who had medical treatment in intensive care unit of clinic of cardiology, Gülhane Military Medicine Academy between June 1-29, 2005. Patients, who stayed in intensive care unit at least 5 days and accepted to join the study, were included. In the study, a data collection form which composed of two parts has been used. A semi-structured questionnaire, which has some introductory characteristics with medical information in the first part and the factors that effect patient’s sleep in the second part, has been used. Results: The mean of ages of patients was 57.9  15.93 and hospitality days in intensive care unit were 8.18  6.13. It has been argued by the patients that their sleep mostly (90%) effected by the noise. Patients stated the reasons of their sleep problems as medical treatments with 95%, light with 85 % and continuous measurement of blood pressures with 75.0%. Conclusion: According to the study results; almost all patients have sleep problems because of different reasons. It is important to know factors affecting patients’ sleep and to take related precaution in order to increase patients’ quality of sleep in the intensive care unit. Key Word: Sleep disturbance; intensive care unit; nursing.