A suspected case of anthelmintic resistance on a farm with Angora and Anglo-Nubian goats was confirmed in a controlled test. Twelve lambs of sheep were infected with larvae cultured from faeces of the goats. The lambs were allocated to four groups: untreated controls and lambs treated 21 days after infection with 5 mg kg-1 oxfendazole, 0.2 mg kg-1 ivermectin or 7.5 mg kg-1 levamisole. The lambs were slaughtered 1 week later and post-mortem worm counts were performed. Benzimidazole resistance was found in Haemonchus contortus, Teladorsagia circumcincta, Cooperia curticei and Trichostrongylus colubriformis with the efficacy of oxfendazole being 68%, 31%, 21% and 48% respectively. No resistance was found against levamisole or ivermectin.