The inflammatory bowel disease (IBD) involves chronic inflammation of digestive tract and it is determined either as Crohn’s disease, that takes place anywhere on the linings of the digestive tract, or ulcerative colitis, that causes inflammation only in the colon. Etiology of IBD remains unclear, but it is known that oxidative damage to biological membranes plays an important role in tissue damaging. Aminosalicylates have been in use for over 60 years in treatment of IBD and their most known representative, sulfasalazine. Besides the inhibition of prostaglandin and leukotriene synthesis and reduction of neutrophil chemotaxis it has been shown that 5-ASA possesses antioxidative properties and is a potential scavenger of free radicals that are responsible for the pathogenesis of IBD. Thus, the aim of this work was to determine the antioxidative power of 5-ASA and its prodrugs. The antioxidative potential of the drugs was determined using HPLC-DPPH method. Scavenging strength of compounds was shown using TROLOX as standard antioxidant and it was expressed as TROLOX equivalent antioxidant capacity (TEAC). Based on the results obtained, 0.1 mM 5-ASA solution showed the strongest antioxidant activity, and than 1 mM sulfasalazine solution. On the other hand, 1 mM solutions of balsalazide and olsalazine showed significantly low antioxidant activity. These results may imply that majority of the antioxidative power of aminosalicylates originate from 5-ASA. It is released from the structure of prodrugs due to enzymatic breakdown of azo bound, therefore, antioxidative effect could be part of therapeutic benefit of sulfasalazine, olsalazine and balsalazide even if their power in produg form was much weaker than 5-ASA itself. The proposed HPLC-DPPH method has been shown to be rapid and effective in determining the antioxidant activity of the aminosalicylate with the purpose of testing additional mechanisms of action of individual representatives of this widely used drug group in clinical practice.