Circulating progenitor cells (CPCs) mobilized from bone marrow will replace the use of bone marrow transplantation because hematopoietic reconstitution is more rapid using the former technique. We report on early and late recovery of hematopoiesis after CPC transplantation in patients with non-Hodgkin's lymphoma (NHL) and analyze the role of variables possibly influencing engraftment. From December 1992 through September 1995, 57 consecutive NHL patients were enrolled in this study. Patients could be divided into 2 groups: the first comprised 32 patients with untreated diffuse large-cell lymphoma and unfavorable prognostic factors; the second comprised 25 patients with resistant or relapsing NHL of low-and high-grade histology. All patients received high-dose chemotherapy (carmustine, cytarabine, etoposide, and melphalan; BEAM) followed by CPC transplantation. In all, 25 patients were treated with granulocyte colony-stimulating factor (G-CSF) after CPC administration. The time to short-and long-term hematologic engraftment and variables correlating with multilineage long-term reconstitution were examined. The time to bilineage (neutrophils and platelets) hematopoietic reconstitution did not differ in G-CSF-treated and-untreated patients. In contrast, the time taken to reach a neutrophil count of 0.5 x 10(9)/1 and a WBC of 1 x 10(9)/1 was significantly shorter in G-CSF-treated patients. Overall, 33 patients achieved long-term, complete trilineage engraftment after a median of 117 days from CPC transplantation. The leukocyte count was the first parameter to reach full engraftment and hemoglobin was the last. According to Kaplan-Meier analysis, 80% of the patients are projected to reconstitute fully at 12 months after transplantation. Univariate and multivariate analyses showed that sustained, long-term hematopoiesis was significantly related to a younger age, an early bilineage reconstitution, and the quantity of CD34+ cells infused.