The present objective was to evaluate Swiss albino mice (Mus muscullus) with Ehrlich carcinoma treated with intrarectal ozone therapy and cisplatin. Twenty-four female mice, approximately 60 days of age, varying between 35g and 40g in weight were divided into four groups, Group G1: Positive control: 2.5mg/kg of cisplatin; Group G2: Ozone-oxygen mix via rectal insufflation (MOO IR); Group G3: 2.5mg/kg of cisplatin + (MOO IR), and Group G4: Negative control with 1ml of saline 0.9%. All animals underwent an eight-day adaptation period. Forty-eight hours after inoculation, the treatments were performed for six days. The mice were euthanized at the end of the experiment and the tumor was removed. There were statistically significant differences between groups for tumor weight. Mean tumor weight was greater in group G4, and lesser in group G3. These significant differences were observed between the negative control and other groups. On histopathology, there were no significant differences between groups. It is concluded that combined ozone therapy and cisplatin was shown to be the treatment where mice with Ehrlich carcinoma had the least tumor weight
