The value of the immunophenotypical subtypes and individual markers was compared with classical parameters in the prognosis of 150 patients with acute lymphoblastic leukemia (ALL). Regarding the immunophenotype, common-ALL had a better prognosis than T-ALL in the children's group. However, in adults the situation was different since both null and T-ALL patients had longer survival rates than the common pre-B group. Moreover, several individual markers add interesting prognostic information, either in ALL as a whole group or within the different immunophenotypes. Thus, the expression of CD10 and TdT had a significantly favourable influence in the outcome of the whole series of patients; within the T-ALL, those cases positive for CD10 also had a longer median survival (33 versus 17 months). In addition, in the common ALL patients group the expression of a relatively mature B marker--CD20--appeared to have a favourable prognosis (27 versus 13 months). Other non lineage specific markers, such as CD9 and CD38 did not seem to influence survival. Regarding the more conventional parameters, our data suggest that the classical age prognostic classification in children (less than 15 years) and adults can be improved using two cut-off points at 11 and 35 years. Moreover, the multivariate analysis showed that this variable, together with FAB morphology and WBC counts were the best combination of parameters for predicting survival. The present study shows that although the immunophenotype helps us in understanding the biological heterogeneity of ALL, having also prognostic implications, there are other clinical and hematological features that yield stronger prognostic information.