Abstract: Bimolane (AT-1727), bis N-morpholinomethyl-piperazinedine 1,2-bis (3,5-dioxopiperazinyl)-ethane, is a derivative of ICRF-154. Experiments Showed that this compound was an effective antineoplastic agent with a wide antitumor spectrum and low toxicity. The main results were as follows:1. AT-1727 showed marked inhibitory effect on mouse tumors of S 180 and S37. At the dose of 25 mg/kg ip or 50 mg/kg po, the growth, of these tumors was almost completely inhibited. Its antitumor action decreased with the decrease in dosage. The 50% inhibitory doses (ID₅₀) of AT-1727 against S37 were 1.88 mg/kg ip and 6.61 mg/kg po. It was also effective against solid mouse tumors of Ehrlish carcinoma, hepatoma and brain tumor B 22 and against L 615 leukemia. The antitumor effect was Schedule-dependent.2. The single intraperitoneal LD₅₀ on mice was 372.8±27.4 mg/kg. The acute toxicity of AT-1727 by oral administration was so low that it can't be determined. The subacute lethal doses(LD₅₀) were 89.3±7.6 mg/kg ip and 243.8±261/mg/kg po. Therefore, the chemotherapeutic indices (LD₅₀/ID₅₀) of AT-1727 by intraperitoneal and oral administration were 47.5 and 36.9 respectively.3. When AT-1727 was injected into dogs intra-muscularly (at doses of 25 and 50 mg/kg/day for 10 days), a slight decrease in leukocyte counts was observed. No significant changes were noted in liver, and kidney function tests and blood platelet count.4. The hemolysin test and graft versus host reaction test were used to monitor the humoral-mediated and cell-mediated immunities respectively. At the dose of 25 mg/kg ip, it depressed the humoral-mediated immunity, but the depressant effect was less than that of ICRF-154 and ICRF-159. The cell mediated-immunity was not depressed by AT-1727.