Colitis is a chronic disease that affects individuals at different ages and affects the quality of their life.  So far, there are three different experimental models for colitis. However, animals in these models die quickly duo to the associates toxicity. The aim of this study is to optimize acetic acid induced acute colitis mouse model with olive oil co-administration. Male albino CD1 mice (n= 91) were randomly divided into 13 groups (n= 7/group). To induce colitis, mice were administrated with different volumes (100 or 200 µl) and concentrations (1%, 2% and 4%) of acetic acid by intrarectal (IR) injection either for three consecutive days or every other day for a total of 6 days. Olive oil (1 µL) was co-injected with acetic acid.  One day later, mice were sacrificed and colon tissues were fixed in 10% formalin for histological examinations. The induction of colitis by acetic acid was dependent on both the volume and the concentration of acetic acid. Interestingly, co-administration of olive oil with different volumes and concentrations of acetic acid, although did not alter the severity of inflammation, it increased the animal survival rate and decreased the associated toxicity.  Injection of co-administration of olive oil with acetic acid is a new modification to enhance the application of this model.