Regardless the mobilization procedure used there is a great variability from patient to patient in the yield of CD34 collections for autologous transplantation. We analyzed retrospectively our non-Hodgkin's lymphoma survey of 60 patients harvested with G-CSF alone after a unique first line chemotherapy; 67% of patients harvested a sufficient number of CD34+ cells during the first attempt of mobilization. The charachteristics of leukaphereses procedures were the same for all the patients. Sex, age, months from the end of chemo- or radio-therapy did not have a significance in influencing mobilization capability, while requirement of G-CSF during chemotherapy was statistically different from failures to successes: 16/20 (80%) of patients failing to reach the target of 2x10(6)/kg CD34+ cells had required G-CSF support during previous chemotherapy versus 18/40 (45%) in the successful group (p 0,005). Our observation supports the hypotesis that individual biological charachteristics of each patient are the most important factors in affecting mobilization capability, deserving further investigation: mobilization schedules tailored on a given patient would minimize the rate of failures, avoiding a second attempt of collection that implies additional economic expenses and negative consequences on the maintenance of dose intensity.