The incidence and nature of pain in 92 children and young adults presenting with newly diagnosed malignancy at the Pediatric Branch of the National Cancer Institute over a 26 month period were assessed. At the time of their initial evaluation, 72 of the total 92 patients were experiencing pain that had been present for a median of 74 days (range 3-821 days) prior to initiation of cancer treatment. In 57 patients, pain had been an initial symptom of cancer; 42 patients had experienced sleep disturbance due to pain. Following the institution of cancer therapy, pain persisted for a median of 10 days. One patient died of malignancy after 5 months without resolution of her pain, and only 4 had persistent pain for greater than 9 months after the start of treatment. Persistent pain is an important symptom of cancer in children and young adults and is often present for long periods before the diagnosis of malignancy is made. Cancer in children usually responds rapidly to modern therapy, and pain usually persists only briefly after the initiation of treatment.