Secondary thrombocytosis appears in patients with various neoplastic and autoaggressive diseases and infections. Thrombocytosis occurrence among 358 patients with NHL and 46 with HD treated at the Department of Haematology of CMKP (Postgraduate Training Centre) and Warsaw Medical School in 1986-1993 is here presented. The 11 patients (3%) among the ones with NHL and the 11 (24%) with HD showed thrombocytosis. Much more frequently the increased thrombocyte count could have been found in patients with low grade T-cell lymphomas (14%) and in patients with Hodgkin's disease. The patients with chronic B-cell lymphocytic leukemia (1%) showed thrombocytosis in very few cases. Thrombocyte count in patients with NHL was not high (mean-596.0 x 10(9)/L median-558.0 x 10(9)/L) which was similar as in those with HD (mean-601.0 x 10(9)/L median-558.0 x 10(9)/L).