Objective: In this study, we aimed to evaluate subjective sleep quality and to determine clinical variables related with sleep complaints for contributing to the analyzing of the relationship between fibromyalgia syndrome and major depression, which may have common pathophysiological mechanisms and can be classified in the same spectrum. Methods: In this study we evaluated 52 fibromyalgia syndrome (FMS), 31 major depression (MD) patients and 37 healthy controls. Patients and controls were evaluated with sociodemographic data form, State- Trait Anxiety Inventory (STAI), Hospital Anxiety and Depression Scale (HAD), Pittsburgh Sleep Quality Index (PSQI), the Van Dream Anxiety Scale (VDAS), Visual Analog Scale (VAS) and Fibromyalgia Impact Questionnaire (FIQ). Results: Depression and anxiety scores were higher in MD group; trait anxiety scores were higher in FMS group. Trait anxiety scores were found similar in FMS and MD groups but higher than control group. In MD group deteroriation of sleep quality was related with depression and anxiety. In FMS group deteroriation of sleep quality was related with pain intensity, severity of anxiety and dream anxiety. Discussion: According to these findings we showed that in both in MD and FMS patients different reasons cause similar impairment in sleep quality. More studies are necessary for understanding the relationships between FMS sleep disorders, pain anxiety and depression which are related with common neurotransmitters such as serotonin and noradrenalin. [Anadolu Psikiyatri Derg 2011; 12(2.000): 93-99]