Clinical significance of hematologic parameters in non-Hodgkin's lymphoma at diagnosis. Three hundred seventeen patients with non-Hodgkin's lymphoma (NHL) (54 low grade, 180 intermediate grade, 76 high grade, and seven unclassified) treated with chemotherapy were evaluated for the presence of hematologic abnormalities at diagnostic staging. Anemia was present in 42%, leukopenia in 6%, thrombocytopenia in 13%, leukocytosis in 26%, and thrombocytosis in 14% at presentation. The presence of bone marrow involvement by lymphoma was more likely to be associated with leukopenia and thrombocytopenia than the absence of bone marrow involvement. Although anemia was slightly more common in patients with bone marrow lymphoma than in those without marrow lymphoma, the difference was not statistically significant. Hematologic parameters were similar for patients with B-cell or T-cell lymphoma. Evidence of bone marrow failure with multiple cytopenias was present in 26 patients (8%). Leukoerythroblastosis was present in 2%. Circulating lymphoma was present in 9.5%. Anemic patients had a shorter survival time than nonanemic patients, whether bone marrow was involved by lymphoma or not. Survival was not affected by the presence of leukopenia or mild leukocytosis, but, in patients without marrow lymphoma, leukocytosis with a leukocyte count greater than 20 x 10(9)/l was associated with short survival length. Thrombocytopenia was associated with short survival time only in patients with bone marrow involvement by lymphoma. Patients with multiple cytopenias or leukoerythroblastosis had short survival times, but the presence of circulating lymphoma did not alter survival when compared with other patients with bone marrow involvement by lymphoma. These data suggest that hematologic evaluation at the time of diagnostic staging of NHL provides useful prognostic information that may have therapeutic implications. 