Tinidazole, a new drug effective against E histolytica, was studied in patients with amoebic liver abscess proved by aspiration of pus. A preliminary open evaluation in fourteen patients provided a cure in all cases. A subsequent comparative study against metronidazole in another twenty-two patients led to a cure in all eleven patients treated with tinidazole and in ten out of eleven patients treated with metronidazole. The response was faster in patients treated with tinidazole. Tinidazole was totally free from side-effects. Tinidazole is a noteworthy addition to anti-amoebic therapy.