The sensitivities of three techniques used for detecting infections of Trypanosoma spp. in frogs (Rana spp.) were compared. In total, 52 of 99 frogs had detectable infections of T. rotatorium, T. chattoni, T. pipientis or T. ranarum. Two or more Trypanosoma spp. were detected in 12 frogs. Microscopic examination of stained kidney impressions (KIT) was more sensitive than either hematocrit centrifugation (HCT) or wet-mount examination (WME) in detecting T. rotatorium and T. chattoni. The HCT was more sensitive in detecting T. pipientis and T. ranarum. Four infections of T. rotatorium that were missed using the HCT were detected using the WME; one of these was missed using the KIT. Success of the KIT may be related to size of the trypanosome while success of the HCT may be related to size, motility or specific gravity of the trypanosome.