Until it has been definitely proved whether or not trichomonads from one source may survive and multiply in other organs, the possibility of auto-infestation remains an important factor in the prevention and treatment of trichomonad infestations, especially the common clinical entity trichomonas vaginitis. The probability of autotransmission depends, however, on the incidence of the organisms in the suspected foci, while the percentage of multiple infestations may be considered as an indication of the extent to which it has occurred. Although the incidence of Trichomonas has been reported by a number of workers, we are not aware of studies of the incidence of trichomonads from these three sources in any one group of individuals. In the present investigation such a study was undertaken among a group of 200 women. All the available laboratory methods of diagnosis, including examination of the fresh specimen by wet smear and stained preparations as well as