In this study, we investigated the analgesic and anti-inflammatory activities of [6-acyl-2-benzothiazolinon-3-yl]acetic acids by the derivatization of the carboxylate moiety into amides. We have tested the analgesic and anti-inflammatory activities of the synthesized compounds in vivo by using p-benzoquinone-induced writhing test and carrageenan-induced hind paw edema model, respectively. Compounds 4h, 4i, 4n, and 4o showed comparable analgesic and anti-inflammatory activities to the references without gastric lesions in the tested animals. In addition, all compounds also tested for their inhibitory activity against cyclooxygenase (COX)-1, COX-2 and 5-lipoxygenase (LOX), but no significant inhibition was observed under assayed conditions.