Abstract: Vincristine is an alkaloid derived from Vinca rosea that its mechanism is to stop the mitosis cell cycle. Therefore, this drug is used in chemical treatment with high multiplication as ovarian cancer, cervical cancer and mammary cancer. This drug can have teratologic effects on fetus. But there is not enough information about pregnant women. Therefore, researchers have been tried in this study to evaluate the toxic effects of this drug in pregnant women on the newborn infants. In this study, researchers choose 40 pregnant mice and sampling units consists of the newborn infants. Firstly, the female mice have been placed near male mice and after observing the vaginal plaque, pregnant mice’s were divided randomly into 2 groups as control and experimental. Mice’s of the experimental group were injected by vincristine (3 mg kg^-1-IP) on day 10th and 16th of gestation. The control group received distilled water. After parturition, the newborn infants were evaluated by the parameters of external morphology anomaly and the data was evaluated by t-test test and SPSS Software. The analysis of the statistics showed that the use of vincristine at during pregnancy on the newborn infants was teratologic effects. In comparing the average of the parameters in the experimental group with control group, there was significant difference (p<0.001).