The research reported in this paper was designed to study the role of plateled-derived growth factor (PDGF) in Hodgkin's disease (HD) and non-Hodgkin's lymphomas (NHL). The PDGF levels in 9 patients with HD and 12 NHL and in a control group consisting of 20 people, was measured by ELISA method. The PDGF values in the disease group of 19 patients were raised. The values of PDGF in the control group were 28.977+/-9 pg/ml, but were measured at 147.083+/-54 pg/ml in HD group and 131.487+/-56 pg/ml in NHL group (p < 0.01). The observation of a 5-fold increase in PDGF values in the disease group when compared to the control group suggests that PDGF could itself be considered as a possible factor in the pathogenesis of HD and NHL. In order to support this, there is a need to design additional studies monitoring PDGF in larger number of patients at various stages of the disease.