Background: Depression and sleep are much related. A majority of people with depression have sleep disturbances. The study aimed to examine the effect of a sleep hygiene educational program on sleep quality among patients with depression. Setting: conduction of the study was at inpatient of Neuropsychiatric Department in Tanta University Hospital. Research design: This study used a quasi-experimental design with a single-group pre/posttest format. Subjects: A convenient sample of 50 patients with depression according to DSM-5 criteria was included in the study. Tools that used in the study were demographic and clinical characteristics Questionnaire, Pittsburgh Sleep Quality Index (PSQI), and Beck Depression Inventory. Results: There was a highly statistically significant positive correlation among the sleep quality index score and total depression score among the studied patients at pre intervention, immediately post-intervention, and 3 months post-program. The study concluded that sleep hygiene educational program improved sleep quality of patients with depression. Recommendations: utilizing sleep hygiene educational program for patients with depression should be considered as an essential part of rehabilitation plans.