For clinical evaluation, 3 different modalities of pain measurement viz. a visual analogue scale, a verbal descriptor scale, and a picture face scale are being compared to evaluate their feasibility of administration and reliability in children of all ages experiencing acute or chronic pain. A cross-modality matching method for pain measurement is also being developed. Ongoing descriptive studies consist of (1) The prospective study of the predictive factors and nature of phantom limb pain and and sensations in patients undergoing amputation and (2) The study of the prevalence and nature of pain in a childhood cancer population at initial presentation. A recently completed study of the etiology, prevalence and nature of pain in our entire patient population had demonstrated that approximately half of the in-patients and one-fourth of the outpatients are experiencing pain at any given time, which was therapy-related rather than tumor-related in the majority of patients. Therapeutic studies in progress are: (1) Study of the efficacy and kinetics of fentanyl given by continous intravenous infusion or transdermally in patients with malignancy who are experiencing pain and (2) Study of the use of nitrous oxide for children with malignancy undergoing painful procedures. A recently completely study has demonstrated the efficacy, kinetics and toxicity of morphine administered by a continuous intravenous or subcutaneous infusion to children and young adults with malignancy who are experiencing moderate to severe pain of various etiologies. Changes in plasma and red cell beta-endorphin occurring during intensive narcotic administration for severe pain are also being analyzed.