The study compared the efficacy of hypnotic "imaginative involvement," behavioral distraction and standard medical practice for the reduction of pain, distress and anxiety in children with leukemia, during bone marrow aspirations. Two age groups of children, 3 to 6, and 7 to 10 years, were randomized to the three treatment groups. Two intervention sessions were given. At first intervention, observational ratings of distress indicated significant reductions for the younger group in the hypnotic treatment, whereas the older group achieved significant reductions in both treatment conditions for observer-rated pain and anxiety. At second intervention, all groups showed reductions and the control group appeared to be contaminated. The hypnotic method with its internal focus had an all-or-none effect, whereas distraction appeared to require that coping skills be learned over one session or more.