ABSTRACTRecently, a third novel feline hemotropicMycoplasmasp. (aka hemoplasma), “CandidatusMycoplasma turicensis,” in a cat with hemolytic anemia has been described. This is the first study to investigate the prevalence, clinical manifestations, and risk factors for all three feline hemoplasma infections in a sample of 713 healthy and ill Swiss cats using newly designed quantitative real-time PCR assays. “CandidatusMycoplasma haemominutum” infection was detected in 7.0% and 8.7% andMycoplasma haemofeliswas detected in 2.3% and 0.2% of healthy and ill cats, respectively. “CandidatusMycoplasma turicensis” was only detected in six ill cats (1.1%); three of them were coinfected with “CandidatusMycoplasma haemominutum.” The 16S rRNA gene sequence of 12 Swiss hemoplasma isolates revealed >98% similarity with previously published sequences. Hemoplasma infection was associated with male gender, outdoor access, and old age but not with retrovirus infection and was more frequent in certain areas of Switzerland. “CandidatusMycoplasma haemominutum”-infected ill cats were more frequently diagnosed with renal insufficiency and exhibited higher renal blood parameters than uninfected ill cats. No correlation between hemoplasma load and packed cell volume was found, although several hemoplasma-infected cats, some coinfected with feline immunodeficiency virus or feline leukemia virus, showed hemolytic anemia. HighM. haemofelisloads (>9 × 105copies/ml blood) seem to lead to anemia in acutely infected cats but not in recovered long-term carriers. A repeated evaluation of 17 cats documented that the infection was acquired in one case by blood transfusion and that there were important differences among species regarding whether or not antibiotic administration led to the resolution of bacteremia.