Intestinal mucositis was carried out by three subcutaneous MTX injections (2.5 mg/kg) in Wistar rats. Rats were treated intraperitoneally with the NOS inhibitors aminoguanidine (AG; 10 mg/Kg) or L-NAME (20 mg/Kg), one hour before MTX injection and daily until sacrifice, on the fifth day. Data represents the median values (and range) of microscopic scores in at least 10 animals per group. *p < 0.05 compared to normal animals (control group); **p < 0.05 compared to animals submitted to MTX-induced intestinal mucositis that received saline, observed on the 5th day. Data were analysed by using Kruskal-Wallis and Dunn's test.