Insomnia and limb pain are common problems in dialysis patients. In addition, restless leg syndrome (RLS) as a specific cause of insomnia and limb pain has been reported in many studies. The purpose of this study was to estimate incidence of insomnia and RLS as a cause of insomnia in these patients. Twenty-six patients undergoing hemodialysis were investigated for insomnia, limb pain and RLS as per the defined criteria. They were evaluated for dialysis quality, dialysis duration, hemoglobin, serum phosphorous, ionized calcium, iron and ferritin levels. These variables between patients with insomnia and those with normal sleep were evaluated by independent "t" test. Without considering the etiology or pathogenesis of insomnia, we evaluated the occurrence of insomnia and limb pain in these patients, and specifically, restless leg syndrome. Insomnia and limb pain were common in dialytic patients. 46% of patients had insomnia. 91% of sleepless group had limb pain as a persistent, annoying complaint. Limb pain was not seen in groups with a normal sleep pattern. Restless leg syndrome was found in 8% of total cases (2 out of 26) and 17% among the insomnia group (2 out of 12). In spite of high incidence of insomnia among patients undergoing regular hemodialysis, role of RLS is trivial. There is a strong relationship between hemoglobin levels and duration of renal replacement therapy to insomnia occurrence.