AG60, a recently introduced anti-cancer compound, was reported to show highly effective anti-cancer activities, when injected with doses from 30 mg/kg to 5 mg/kg.The purpose of this study was to know the lower effective doses of AG60, and to give the informations for preparing more advanced therapeutic tools for anti-cancer war. Ehrlich cancer cells were inoculated in the subcutaneous tissue of inguinal region of ICR mice, and saline (treated control groups) or AG60 (experimental groups) were injected daily. Animals of experimental groups were injected subcutaneously with doses of 0.2 mg/kg, 0.5 mg/kg, 1.0 mg/kg, or 2.0 mg/kg body weight, according to their subgroups. Five mice from each subgroup were sacrificed on 1 week, 2 weeks, 3 weeks following the first injection. Seventy minutes before sacrifice, each mouse was injected with 0.7 microCi/g body weight of 3H-thymidine (Amersham Lab.) through tail vein. After sacrifice, cancer masses were fixed in 10% formalin solution for autoradiography and light microscopy, and in 2.5% glutaraldehyde-1.5% paraformaldehyde solution, followed by post-fixation in 2% osmium tetroxide solution, for electron microscopy. The observed results were as follows: Autoradiographic observations show, 1. Labelled cancer cell indices of the experimental groups received AG60 were decreased around to 80% (0.2 mg/kg), to 74% (0.5 mg/kg), to 75~60% (1.0 mg/kg), and to 70~50% (2.0 mg/kg), as compared with those of the controls. 2. The contents of silver grains were dramatically decreased nearly to 35% (0.2 mg/kg), to 20% (0.5 mg/kg), to 21~16% (1.0 mg/kg), and to 20~15% (2.0 mg/kg), as compared with those of the controls. 3. Total granular content in 100 cancer cells on the third week of the experiment decreased nearly to 30% (0.2 mg/kg), to 15% (0.5 mg/kg), to 10% (1.0 mg/kg), and to 8% (2.0 mg/kg), as compared with those of the controls. Histological observations show, 1. AG60 induces large amount of apoptosis on Ehrlich cancer cells. 2. Following the treatment with AG60, multinuclear cells or giant cells were increased in number. Comparing by autoradiography and histology, multinuclear or giant cells were interpreted as those cells supplied by poor amounts of thymidine, or almost no new DNA content. Electronmicroscopic readings show, 1. AG60 induces numerous macroclefts and microclefts within the nuclei of Ehrlich cancer cells. 2. AG60 induces numerous apoptosis among Ehrlich cancer cells. 3. Apoptotic bodies are phagocytosed by adjacent cancer cells or by macrophages. From the above results, AG60 is expected to be a very successful anti-cancer candidate. And it is suggested that combined or cocktail therapy including AG60 may greatly improve the anti-cancer therapy on certain kind of cancer.