Abstract
Card reports that serologic examination of pleuropneumonia-like organism strains isolated from the human genital tract showed that they all belonged to the same serologic group and could be distinguished serologically from PPLO isolated from the human mouth and from various animal species. In venereal disease clinic patients antibodies were found in 34%, in blood donors and children in only 2%. Forty-five percent of venereal disease clinic females had antibodies whereas only 18% of males revealed them. The distribution of antibodies roughly paralleled the frequency with which PPLO could be isolated from the uro-genital tract.