Prostaglandin E1 (PGE1) is known to have a strong vasodilator effect and to block coagulation and inflammation in high concentrations. The aim of this study has been to investigate whether PGE1 has an inhibitory effect on inflammation in experimental colitis. Experimental colitis was produced by rectal instillation of 10% acetic acid in 60 rats. These were divided into prostaglandin (PG) (n = 30) and control groups (n = 30). Twelve hours later, an intraperitoneal injection of 2 micrograms PGE1 in 1 ml saline was given to the PG group and 1 ml saline to the control group. This was repeated daily and the animals were sacrificed in groups of 10 on the 3rd, 7th and 10th day. Histopathological examination and hydroxyproline determination for assessment of collagen synthesis were performed. PGE1 significantly decreased inflammation on third day with the hydroxyproline level significantly higher in the PG group compared with the control group (p < 0.05). This difference was however not significant at the 7th and 10th day. The present study supports a beneficial role for prostaglandin E1 in reducing the severity of colonic inflammation following chemically induced colitis but only in the early stages of development.