The time it takes to harvest bone marrow before transplantation could be reduced significantly by increasing the temperature of the operating room by 8-10 degrees C, to about 28-30 degrees C. In healthy donors, the collected volume of marrow was increased from 22.45 to 36.31 mL/min; in patients who received chemotherapy previously, from 21.67 to 29.98 mL/min. The time to collect a volume of 1200 mL marrow could be reduced significantly, from 57.78 to 38.25 minutes in healthy donors and from 71.07 to 43.36 minutes in patients who received chemotherapy previously, without any loss of quality of the sampled marrow. Operation time and thereby time of anesthesia could be reduced significantly by heating the operating room to a temperature of 28-30 degrees C. Harvesting at higher room temperature did not result in any adverse side effects for the patients. The procedure to increase the body temperature could be simplified by using electric blankets and aluminum foils for wrapping to avoid heat emission.