This research is designed to investigate the influence of N-benzoiloxymethyl-5-fluorouracil on p53 protein expression and apoptotic activity in 7.12-Dimethylbenz(a)anthracene (DMBA) induced in Breast Cancer Rats. Thirty rats were divided into six groups i.e control group, DMBA group, 5-fluorouracil  group and three treatment groups of N1- benzoiloxymethyl-5-fluorouracil at 2,77; 5,54; 11,06 mg/200gbw dosages in intra peritoneal during a week. DMBA were given orally for 5 weeks with 2 x 20 mg/ kgbw dosages and 11 weeks incubation with 20 mg/kgbw dosages. Treatment groups were given i.e. administration drugs for a week. The mammae tissues examine in the 8^th day of treatment and stained with haematoxylin eosin for morphological quantitative analysis and immunohistochemistry to observe the existence of p53 and apoptotic activity in the breast cancer mice. The research result indicates that in histology blood smear slice of breast tissue in DBMA control group has pleumorphie, hypercromatin, and higher mitosis than in 150 µmol/kgBB 5-fluorourasil and 75,150, 300µmol/kgBB N1-benzoiloksimetil-5-fluorourasil group. Similiarly in immunohistochemistry, it is indicate that 2,73 mg/200gBB 5-fluorourasil and 2,77; 5,54; 11,06 mg/200gBB N1-benzoiloksimetil 5-fluorourasil treatments can increase p53 protein expresion and the number of apoptotic mice breast cancer cell rather than in DBMA control group.