Yunkang oral liquid (YK) had an obviously anti-abortional effect on the abortional testing model of both rats and mice, which was induced by acupuncture and oxytocin (P < 0.05, P < 0.01); there is no statistic difference between the effect of progesterone and the effect of YK. The results showed that YK could relax obviously the uteri of both rats and mice in vitro and the uteri of rabbits in vivo. It also could antagonize the effects of oxytocin and acetylcholine on animals uteri in vivo and in vitro (P < 0.01, P < 0.05). The acute toxicologic test showed the maximal tolerance dose of ig. in mice and rats were higher than 240 g/kg and 96 g/kg respectively. The LD50 in mice (ip.) was 61.56 +/- 5.29 g/kg (p = 0.95). Subacute toxicologic test for 8 weeks of continuous drug feeding among rats did not show obvious toxicity. Mutagenicity test also showed negative results. Feeding to pregnant rats with YK did not result in teratogenicity to the offsprings. The growth and development, memory of filial generations were not affected, either. So Yunkang oral liquid, a Chinese compound recipe, has a safe and reliable effect of anti-abortion.