The synthesis of isoindoline analogues of indapamide is described. These substances (4a,c,d) were tested for diuretic activity, and 4a was found to be comparable in potency to indapamide. The positional isomers 3a-i of 4'-chloro-5-methoxy-3-biphenylylacetic acid [l (DKA-9), R = 4-ClPh; R' = Me01 which is a newly developed nonsteroidal antiinflammatory agent, have been prepared and evaluated for antiinflammatory and analgesic activities using both the carrageenan-induced rat paw edema and AcOH writhing assays. The 3- and 4-biphenylylacetic acids 3a,d, which closely resemble 1 (R = 4-ClPh, R' = MeO) structurally, showed, by far, excellent activities compared with the other isomers in these assays. However, none of the compounds tested was more active than 1 (R = 4-ClPh; R' = MeO). In this series of compounds, structural requirementa for good antiinflammatory activity seemed to be parallel to those for analgesic activity.