A series of some novel 2,4-diaryl-3,5-bis(arylimino)-1,2,4-thiadiazolidine derivatives were synthesized and evaluated for anti-inflammatory activity. In the SAR study, the phenyl ring on 3 and 4 position of 1,2,4-thiadiazolidine ring substituted with chloro, nitro and methoxy groups showed better activity. The title compounds were synthesized from two steps; the first step involved the synthesis of diaryl substituted thioureas then, it was cyclised to give the 1,2,4-thiadiazole system in the presence of oxidizing agent (hydrogen peroxide and concentrated hydrochloric acid) in the second step. The purity of the synthesized compounds were judged by their C, H and N analysis and the structure was analyzed on the basis of IR, H1NMR, C13 NMR and Mass spectral data. The anti-inflammatory activity of new compounds was determined by λ-Carrageenan induced mice paw edema method using diclofenac sodium as a standard. Among the compounds tested four compounds, B2 (2,4-diphenyl-3,5-bis(3-nitrophenylimino)-1,2,4-thiadiazolidine), B4 (2,4-diphenyl-3,5-bis(3-chlorophenylimino)-1,2,4-thiadiazolidine), B6 (2,4-diphenyl-3,5-bis(4-methoxyphenylimino)-1,2,4-thiadiazolidine) and B7 (2,4-diphenyl-3,5-bis (2-methoxyphenylimino)-1,2,4-thiadiazolidine) were the most active compounds in these series.