HDCS vaccine has been in official use in the F.R.G. for pre- and post-exposure vaccination of man, after having shown its superiority to the Hempt and duck embryo vaccine--as far as compatibility, antigenicity and protective capacity is concerned--since February 1977. HDCS vaccines of both manufacturers, Mérieux/Lyon and Behring/Marburg, did not produce any severe side effects in about 5000 vaccinees in West Germany when conditions of vaccine production were properly observed. The lack of neuropathogenicity of vaccines is stressed. Contamination by bacterial lipopolysaccharides, however, resulted in endotoxin shock in 32 out of 35 vaccinees with one vaccine lot. Testing for pyrogenicity of every vaccine lot should be carefully observed in future. When comparing antigenicity of different vaccine lots of both manufacturers, individual titers of complement-fixing and neutralizing antibodies were correlated with the antigenic values of the vaccines. Duration of immunity after one course of vaccination is approximately 2 years and can be extended by only 1 booster injection for an additional 3 years. Protective capacity of HDCS vaccine (using Essen scheme, 6 applications) seems to be very pronounced. So far, between 1973-1977, 68 individuals under severe risk were vaccinated post-exposure in West Germany and 45 individuals in Iran from 1975-76. No cases of rabies occurred in the vaccinees. HDCS vaccine in man induces a very early antibody response with appearance of IgM rabies specific antibodies on day 3, and IgG rabies specific antibodies on day 7 and an early IgM/IgG antibody conversion at that time.