This study was aimed to investigate the effects of commonly prescribed NSAIDs, flunixin meglumine, carprofen and meloxicam, on the concentrations of free triiodothyronin (fT(3)), free thyroxin (fT(4)) and thyroid stimulating hormone in healthy rabbits. For this purpose, 32 New Zealand rabbits of similar age and weight and different sex were divided into four equal groups of eight. Rabbits in control group (n=8) received serum physiologic, animals in group FLU (n=8) were given flunixin meglumine at dose of 1.1 mg/kg, group CAR (n=8) received 2.2 mg/kg carprofen and group MEL (n=8) was given 0.2 mg/kg meloxicam intramuscularly (IM) for 5 days. Blood samples were collected 4 hours after each injection from vena auricularis into plain vials to determine hormone concentrations. Following separation of serum by centrifugation at 3000 rpm for 10 minutes, commercially available ELISA kits for free T(3), freeT(3) and TSH were used for determination. Results shown that fT(3), and fT(4) concentrations increased throughout the study period of 5 days within 3 treatment groups (p<0.001) and these increases were also significant when compared to control group (p<0.05, p<0.01 and p<0.001) while TSH concentrations decreased in treatment groups (p<0.001) during the study period and it was also lower than the control group (p<0.001). In conclusion, use of NSAIDs can alter thyroid hormone concentrations and thus these alterations should be considered in diagnosis and therapy in order to avoid misleading.