Thrombocytosis has been reported during chemotherapy with gemcitabine (GEM). A 71-year-old male patient who developed asymptomatic thrombocytosis (1,749 x 10(3)/microl), secondary to GEM chemotherapy for lung carcinoma, was submitted to therapeutic plateletpheresis (TP). We adapted the software of the productive dual-needle plateletpheresis of our cell separator in order to reduce the procedure time and the plasma volume harvested. With 2 low-volume TP in 24 h, we achieved a 55% global reduction of the platelet count. While there are no accepted indications for prophylactic plateletpheresis in asymptomatic patients and the measured count should not, by itself, determine whether platelet reduction is indicated, a drastic reduction of an extremely high platelet count, especially if obtained with a relatively short procedure, can be important to prevent acute severe sequelae.