Abstract: The present study was conducted in order to evaluation of hematologic, biochemical and endoscopic findings in horse following long period use of non-steroid anti inflammatory drugs. About 36 heads male Arab horses were divided to 3 groups consisted of 12 horses with an identical feeding, management and activity conditions. Physiological serum, 1.1 mg kg^-1 flunixin meglumine and 3.3 mg kg^-1 ketoprofen were injected intra muscular for 10 days, respectively for group 1-3. On zero time (before injection), days of 2, 4, 6, 8 and 10 bloods sampling was done from the horses’ vena cava and the samples’ serum was separated by centrifuging then the serums were freezed. Hematologic tests and some of biochemical tests were done on blood samples followed by endoscopic tests on horses for evaluating gastric viscera and gastric ulcers. Hematologic changes such as red and white blood cells count and haematocrit percentage were not meaningful in three groups. In groups 2 and 3 the average level of total protein, albumin, creatinine and urea serum levels demonstrated a meaningful increase with increasing of drug using period (p<0.05). The heart troponin serum level in group had a meaningful increasing since 6 and 8th day in groups 2 and 3, respectively (p<0.05), this increasing level was multifold in both groups on 10th day. The average level of CK, ALP, ALT, AST and GGT enzymes serum concentration in understudying horses had a meaningful increase by increasing the period of the used drug (p<0.05). Based on endoscopic findings all horses of group one had healthy gastric viscera after 10th day but 8 horses in group 2 had healthy gastric viscera, 3 horses suffered from I grade gastric ulcer and one horse suffered from II grade gastric ulcer. About 6, 4, 1, 1 horses of the 3rd group had healthy gastric viscera, I grade gastric ulcer, II grade gastric ulcer and III grade gastric ulcer, respectively. The result is that the use of flunixin meglumine in long time causes to increase total protein, albumin, creatinine and urea, heart troponin and CK, ALP, ALT, AST, GGT but there is no meaningful change in hematologic findings and causes to horse gastric viscera injury. Therefore, liver, renal and digestive injuries are some of long term influences of the drugs on horse.