Improving prognosis for many forms of childhood cancer has resulted in increased attention on the quality-of-life experience. Conditioned anxiety and pain associated with recurrent diagnostic and treatment procedures have been identified as major sources of distress in children with malignant disease. To evaluate the efficacy of various psychological strategies for distress reduction, valid situation-specific measurement tools are required. A 25-item behavioral observation scale of distress during a selected procedure, bone marrow aspiration, was developed. Observations of 115 children with leukemia, ranging in age from 8 months to 17 years, 9 months, were collected. Trained observers were utilized, achieving an inter-rater reliability above .90. Results indicated clear age differences, with younger children exhibiting more distress behaviors and more gross motor behaviors than older children. Females exhibited more behaviors than males across age groups, also displaying more emotional interactivity than males. Behavioral observation and independent nurse ratings correlated .66. A replication and extention of the first study included a self-report measure of general affective state during the procedure. With a sample of 151 children, the self-report measure correlated significantly with objective behaviors and nurse ratings, but only for children above age six. Self-report scores, as with behavioral indicators, generally decreased with increasing age. (Author)