Spiny softshell turtles (Apalone spinifera), common snapping turtles (Chelydra serpentina), and red-eared sliders (Trachemys scripta elegans) were surveyed for leeches at 16 sites across Texas, U.S.A., from March to December of 2017. Five species of leeches were found (3 from 15 A. spinifera sampled, 4 from 9 C. serpentina sampled, and 3 from 55 T. scripta elegans), representing 3 new host records and 1 new locality record. Leech abundance was also compared to water parameters (ammonia, carbon dioxide, chloride, dissolved oxygen, hardness, nitrite, nitrate, pH, salinity, temperature, and turbidity) and qualitative environmental variables (vegetation, sediment, latitude, longitude, season, and water body) through principle components analysis, stepwise regression, and model selection. We found significant effects of sediment composition and seasonality on leech abundance. This study adds novel data on leech–host associations, distributions, and diversity in Texas.