Between 1992 and 1999, 105 unrelated allogeneic bone marrow collections from 103 volunteer donors (65 males and 38 females; median age 33 years) were carried out in three northern Italian centers (Verona, Bolzano and Padova) affiliated with the Italian Bone Marrow Donor Registry (IBMDR). The average volume of BM collected was equivalent in both genders (1143.1 ml for males and 1054.2 ml for females; P = 0.1), although the average volume collected for unit of body weight and the average post-collection blood volume depletion was higher in females (respectively 17.1 ml/kg and 14.2% in females, 14.8 ml/kg and 12% in males; P= 0.01 and 0.03). There was no statistically significant difference between males and females in the total number of nucleated cells collected. We did not record any acute life-threatening event during or after the bone marrow collections. The most frequent complaint was pain at the collection site (77%) followed by the onset of fatigue (38%) and nausea and vomiting (25%); all of these were short-term problems. Hospitalization was short (average 20.2 h) and donors started their normal daily activities after an average of 5.4 days. We also monitored Hb, serum ferritin levels, WBC and platelet counts in the post-collection period (average follow-up 40.1 months). All donors signed a written informed consent for a further bone marrow collection, if needed. Our findings confirm the short- and long-term safety of allogeneic bone marrow collection in volunteer donors.