A nutritional and metabolic assessment of a cardiopulmonary bypass technique without donor blood was made in 23 patients undergoing open heart surgery (non-donor blood group). For comparison, 14 patients receiving cardiopulmonary bypass with donor blood prime (donor blood group) were also evaluated. 1)Serum transferrin level showed significantly more rapid recovery in the non-donor blood group compared to the donor blood group on the 7th post operative day. 2)Total protein, serum albumin, arm muscle circumference, creatinine-height-index and triceps skin fold showed no significant differences between the two groups. 3)Total lymphocyte count as an indicator of immune status showed a significant increase in the non-donor blood group on the 3rd post operative day. 4)The recovery from the postoperative hypermetabolic state was more smoothly achieved in the non-donor group blood group than in the donor blood group. In conclusion, the cardiopulmonary bypass technique without donor blood is a safe and effective means of open heart surgery, not only saving blood but also preventing undue, infectious and/or hypersensitive diseases.