Cytogenetic patterns in correlation with cytologic, biomolecular and clinical findings were studied in 45 adult patients with AML expressing at least one of the following lymphoid associated markers (LM): CD2, CD7, CD10, CD19, CD22, TdT. Four cytogenetic groups were recognized: group I, including 8 patients with 11q23 rearrangements; group II including 5 patients with the Ph chromosome; group III, with 19 patients and aberrations of the "myeloid type" including 4 cases with aberrations of chromosome 13, 3 cases with 1q and 7q anomalies, 2 cases with trisomy 11q; group IV, including 13 patients with normal karyotype. Patients showing extensive lineage infidelity were encountered more frequently in cytogenetic groups I and II than in groups III and IV. Two of 4 cases with aberrations of chromosome 13 showed two or more lymphoid features either at immunophenotyping or at biomolecular analysis of the configuration of lg and TCR genes. Patients with 11q23 rearrangements and with the Ph chromosome were generally young, presented with high WBC count and had low complete remission rate. Survival in Ph chromosome positive patients was uniformly short. We conclude that, although there is no cytogenetic anomaly specific for AML with LM, chromosome findings may be clinically relevant in AML with LM. A morphologic, immunologic and cytogenetic classification of AML with LM may constitute a working basis for future studies aimed at a better definition of clinicopathological features and optimal treatment strategy for these leukemias.