Transfusion frequency rates were determined in a patient population of 229 having undergone major oral and maxillofacial surgery as follows: tumor surgery (TU, n=54), orthognathic surgery (OR, n=41), preprosthetic surgery (PR, n=7), reconstructive surgery (RE, n=49) and traumatology (TR, n=78). Duration of surgery was in the range 2 - 20 hours. Autohaemotherapy was of particular significance for orthognathic operations. Statistical evaluation was via variance analysis and the chi-squared test (significance level alpha=0,05). The resulting transfusion frequency rates were as follows: TU 55.6%, OR 31.7%, PR 14.3%, RE 12.2% and TR 5.1%. Transfusions were significantly more often needed in the following operations: TU>OR/RE/TR and OR>TR. The number of transfusions was found to increase as operation time increased (0- 2h: 0%, 2- 4h: 1,5%, 4-6h: 12,9%, 6-8h: 34,5%, 8-10h: 60% and 10h: 100%). The value for 10h was statistically significantly greater than the values for the remaining operation times. The following laboratory values for the non-transfused patients were statistically significantly different compared to those receiving transfusions (shown in brackets): haemoglobin preoperative 141 (129) g/l, haemoglobin postoperative 122 (111) g/l, serum calcium 2.49 (2.38) mmol/l and leucocytes 9.23 (7.98) G/l. 96.8% of all autohaemotherapy applied to the orthognathic patients. Retransfusion was carried out in 35.5% of the cases. Heterotransfusion of blood is to be decided at a probability greater than 5%. This can be assumed in oral and maxillofacial surgery in the subdisciplines tumor, orthognathic and reconstructive surgery, as well as operations taking 4-6 hours and longer. Autohaemotherapy provides an alternative. A further outcome of the investigation was that low haemoglobin, serum calcium and leucocyte values more often resulted in transfusions. Schlagwörter: transfusion frequency rates, oral and maxillofacial surgery