Two thousand, three hundred and three patients who had undergone major orthopaedic surgery were statistically analysed for the incidence of complications comparing three regimens of prophylaxis and coexisting diseases; 2090 patients did not present postoperative complications. PTE occurred in 0.65% (one fatal). The mortality rate was 0.34% and the incidence of haemorrhage (haematoma and one gastric haemorrhage) was 3.8%. Patients treated with indobufen had a shorter hospital stay and the need for homologous blood transfusions was lower than for patients treated with calcium heparin. The rate of PTE was notably different in the three groups, being lower in the group treated with enoxaparin, although this result was not found to be statistically significant.