Attempts were made to correlate virus excretion, joint symptoms and antibody response with human leukocyte antigens (HLA) in seronegative adult women given attenuated rubella vaccine. No association was shown between HLA antigens of the A and B loci and excretion of either high or low titres of RA27/3 vaccine among 26 volunteers. However, virus excretion was influenced by such factors as the time of day at which specimens were collected and the method of virus isolation. Our study therefore failed to confirm the hypothesis that certain persons are good 'spreaders' of rubella virus and that this capacity is associated with HLA-A1 and B8. The study of joint symptoms following vaccination with Cendehill, HPV77.DE-5, RA27/3 or To-336 vaccines showed no association between such symptoms and HLA antigens. However, joint symptoms occurred within 7 days of the onset of menstruation in 33 of 47 (70%) vaccinees (P less than 0.01) and it is therefore suggested that hormonal factors must play a role. No association between HLA antigens and haemagglutination inhibition (HAI) antibody titres, 8 weeks after vaccination with RA27/3, was found amongst 34 volunteers.