Inactivation of selected bovine parasites was measured quantitatively during anaerobic digestion of bovine slurry in small-scale batch digesters. Mesophilic (35°C) and thermophilic (53°C) anaerobic digestion accelerated the inactivation of parasitic nematodes, compared to survival under conventional storage at outdoor temperatures (20° and 4°C). Estimated by in vitro cultivation and baermanization, eggs of Cooperia oncophora lost viability within 2 to 5 days at 35°C and in less than 15 min at 53°C. Dictyocaulus viviparus larvae did not survive 1 week at 35°C. Eimeria oocysts were morphologically unaffected after 50 days at 35°, 20°, and 4°C and after 24 h at 53°C.