Because they are ectothermic, immune function in reptiles is affected by temperature. The physiology and transmission of parasites can also be influenced by temperature. In red-eared slider turtles (Trachemys scripta), previous studies have separately examined the effect of temperature on B cell function in vivo and the correlation between antibody levels and parasite prevalence. This study aimed to examine the interaction of thermal preference of the sliders, antibodies, and intestinal parasites in an individual. Plasma and mucosal samples were collected and will be used to measure total antibody levels. Fecal samples were collected and the presence of intestinal parasites was determined. Thermal preference was determined by placing a turtle into a box with a heat gradient for three hours. Temperature was recorded every minute using a Thermochron iButton recording device attached to the carapace. Maximum temperature (Tmax), average temperature (Tavg), and minimal temperature (Tmin) were determined for the last hour. Tmin was higher in turtles with intestinal parasites. Tmax and Tavg were not significantly higher in turtles with intestinal parasites. Females had significantly higher Tmax and Tavg (but not Tmin) than males. The higher minimum temperature of turtles with parasites may be a behavioral fever to aid in immune activation and promote the ability to clear the parasites. Alternatively, a higher temperature may lead the turtles to be more active and thus the turtles may be exposed to more parasites.