Vaccination against rabies after exposure to the risk of contamination is currently performed according to the WHO recommendations: 6 injections in 6 visits. We have studied the serological effectiveness of a simplified method using the human diploid-cell rabies vaccine: the vaccine is injected subcutaneously at the rate of 2 doses on day 0, then one dose on day 7 and one dose on day 21. Fifty subjects were vaccinated, and antiglycoprotein antibodies were assayed in serum by the immunoenzymatic technique (EU/ml). Seroconversion with titres above 0.5 EU/ml was observed in all subjects. The antibody titres were 0.127 +/- 1.57, 11.31 +/- 8.87, 10.2 +/- 7.55, and the numbers of subjects with protective titres were 0/50, 11/50, 46/47 and 36/37 on days 0, 7, 21 and 90 respectively. No undesirable side-effect was recorded. The good results obtained with this 2+1+1 vaccination schedule (4 injections in 3 visits) suggest that the recommended method of post-exposure vaccination could be replaced by this simplified method.