After an initial blood and thorax examination, 97 children with ALL were divided into "high risk" and "low risk" groups. From the 20 new "high risk" patients seen between 1972 and 1975 about one quarter were still alive 3 years later, the corresponding proportion from 37 "low risk" patients being about two thirds. Despite increased therapy, the number of early relapses does not appear to have decreased in the new "high risk" cases seen between 1976/77. An investigation of cell surface markers established that T-ALL always occurred in the "high risk" group, whereas B-negative/T-negative ALL was found not only in the "low risk" group but also occasionally in the "high risk" group.