Childhood acute lymphocytic leukemia (ALL) with partial deletion of the short arm of chromosome 9 (9p-), particularly in the p21-22 region, associated with bulky disease, has been regarded as a possible subgroup of ALL. We have reviewed clinical and cytologic data in 128 cases of ALL (childhood and adult). Four of them had 9p anomalies. Two patients had a deletion in the 9p21 region associated with another deletion (9p13----pter) in one case and with t(1;19)(q21;p13) in the second patient. A third patient had a t(9;14)(p21;q12) balanced translocation associated with 14q22----qter deletion; the last patient showed a t(5;9)(p14;q21) unbalanced translocation also associated with 14q deletion. All four patients had lymphomatous ALL, but immunophenotype was non-T, in the four cases, (non-T, non-B in two patients and common ALL in the two remaining cases). Acute lymphocytic leukemia with 9p anomalies appears relatively frequently and is usually associated with poor prognostic features (i.e., bulk disease and high leukocyte counts) but does not seem restricted to childhood and T-cell lineage.