In order to observe the curative and side effects in malignant hematologic diseases treated with autologous peripheral blood stem cell transplantation (auto-PBSCT) combined with halotype lymphocyte infusion, auto-PBSCs were mobilized, harvested and stored at -196 degrees C from patients in first CR or PR with intensive chemotherapy (Ara-C 1.0 g/m(2) x 5 days or cyclophosphamide 60 mg/kg x 2 days) and G-CSF. Unpurged auto-PBSCs were infused when patients received the conditioning regimen with busulfan, total irradiation or cyclophosphamide. Halotype lymphocytes [mean 5.0 x 10(7)/kg, (4.5 - 6.5) x 10(7)/kg] irradiated with 7.5 Gy were infused to patients when WBCs were more than 1 x 10(9)/L. Hematopoietic recovery and survival of patients were observed. The results showed that in 12 cases accepted this protocol, five patients with acute non-lymphocytic leukemia got to durable remission, of which 2 had durable remission of more than 50 months. One of three patients with non-Hodgkin's lymphoma IVb reached durable remission, and two relapsed and died on 4 and 6 months after treatment, respectively. Two CML patients were also achieved durable remission. One patient with multiple myeloma relapsed on 36 months later, but he still survived disease-free with treatment of thalidomide. In a follow-up survey of 25 months, the disease-free survival was 83%. No severe side effects were observed except platelet delayed recovery after halotype lymphocyte infusion. STR-PCR analysis showed that infused donor lymphocytes disappeared in 3 recipients at 72 hours after infusion. It is concluded that auto-PBSCT combined with halotype lymphocyte infusion could decrease the relapse of malignant hematologic diseases and improve the effect of auto-PBSCT. Recovery of platelet, however, could be delayed by halotype lymphocyte infusion.