Synadenium umbellatum Pax, popularly known as "cola-nota", is a medicinal plant that grows in tropical regions. The latex of this plant is used against various diseases, such as diabetes mellitus, leprosy, tripanosomiasis, leukemia, and several malignant tumors. The mutagenic, antimutagenic, and cytotoxic effects of the latex of this plant were investigated by measuring the frequency of micronuclei in mice bone marrow cells. To evaluate mutagenicity, the animals were treated with four doses of latex (10, 30, 50, and 100 mg/kg body weight). To study the antimutagenic activity, the animals were simultaneously treated with latex and mitomycin C (4 mg/kg). The cytotoxicity was evaluated by polychromatic and normochromatic erythrocytes ratio. Our results showed a significant increase of frequency of micronucleated polychromatic erythrocytes (MNPCE) compared to the negative control group (p < 0.05). Concerning antimutagenicity, the doses of 10 and 30 mg/kg co-administered with mitomycin C showed significant decrease in MNPCE frequency compared to the positive control group (p < 0.05). However, no significant reduction in MNPCE frequency (p > 0.05) was detected at the doses of 50 and 100 mg/kg. Under our experimental conditions, the results obtained indicate strong mutagenic and cytotoxic activity of S. umbellatum latex except the dose of 10 mg/kg and moderate antimutagenic effect at lower doses.