The objective of the study was to evaluate the anticancer activity of Acetone root extract of Canthium parviflorum Lam. (ARECP) in N-Nitroso N-methyl urea (NMU) induced mammary carcinoma in female Sprague-Dawley rats. Thirty virgin female Sprague-Dawley rats of 55 day old were divided into five groups (normal control, disease control, ARECP 200 mg/kg, ARECP 400 mg/kg, tamoxifen10 mg/kg) of six animals each. The mammary carcinoma was induced by two intraperitoneal doses of N-Nitroso N-methyl urea (NMU) (50mg/kg/body weight each) in 0.9% Nacl (maintained at 40C) at 55 day of age and 4 week after the prior administration. The drug ARECP was administered in two doses, 200 mg/kg, and 400 mg/kg orally and compared with the oral dose of tamoxifen (10 mg/kg). ARECP 200 mg/kg, 400 mg/kg, and tamoxifen10 mg/kg decreased the tumor incidences by 33.33%, 50%, and 83.33% and the total number of tumors in group by 33.33%, 60% and 93.33% respectively, when compared to the disease control. ARECP 200 mg/kg, 400 mg/kg, and tamoxifen 10 mg/kg decreased the average tumor burden by 65.06%, 92.16% and 95.72% and average tumor volume by 62.25%, 85.18%, and 93.73% respectively, when compared to disease control group. The results concluded that ARECP prevent the mammary carcinogenesis induced by N-Nitroso N-methyl urea in female Sprague-Dawley rats.