Sleep disturbances are commonly reported by children receiving chemotherapy for leukemia. Sleep patterns before diagnosis and during induction chemotherapy were evaluated in 38 children (7 to 18 years old). Child Sleep Assessment (CSA) was used to evaluate sleep patterns prior to diagnosis. Sleep diaries and actigraphy were used during chemotherapy. Adolescents went to bed later and awakened later than school-age children before diagnosis and during chemotherapy. During chemotherapy, children averaged 60 minutes of nighttime wake time. The early recognition of sleep problems associated with disease, treatment, and age is important for school-age children and adolescents with leukemia.