The morphology of acute lymphoblastic leukemia is of prognostic significance, but due to the qualitative subjective nature of the assessment, disagreement between pathologists may be considerable. In order to investigate the adjuvant potential of morphometry, the present study was undertaken. Morphometry was applied in 21 children between 2 and 10 years of age with acute lymphoblastic leukemia (ALL) with a follow-up of at least 5 years. Of these, 9 patients died, 12 (57.1%) survived for at least five years (maximally 12 years). Morphometry appeared to have an important prognostic value, independent of the FAB classification currently in use. Combination of the nuclear-cell area ratio and the cell area gave a rather good discrimination, although these quantitative data from a morphological continuum. The positive results of this pilot study point to the necessity of evaluating the data on a larger material.