The present study was undertaken to evaluate the frequency, characteristics and actuarial risk of secondary acute non lymphoid leukemia (s-ANLL) in 141 patients treated for non Hodgkin's lymphoma with different modalities. One hundred and twenty-four patients received chemotherapy according to PROVECIP protocol. Of these, 15 also received as induction treatment a local nodal irradiation and 33 an extended field radiotherapy. Seventeen out of 141 were treated by total body irradiation. Of these, 15 relapsed and received salvage chemotherapy. Sixteen of the 124 patients treated with PROVECIP also underwent different chemotherapeutic programs as salvage treatment. Of the entire population studied, 2 patients developed an s-ANLL, 45 and 63 months after diagnosis of NHL. The type of treatment significantly affected the occurrence of s-ANLL, since both leukemias occurred in patients treated with total body irradiation, given alone or followed by chemotherapy. The actuarial risk at 8 years was 5.24% in the whole group, whereas it greatly increased in the group of patients treated with total body irradiation (24%). Conversely, no risk was found in the group treated with PROVECIP, alone, with additional chemotherapy, or with associated local or extended field radiotherapy.