A series of [(6,7-dichlorobenzo[b]thien-5-yl)oxy]acetic acids and their corresponding 1,1-dioxides were synthesized and evaluated for diuretic activity in the acute saline loaded mice (ASLM) and hypotensive activity in the spontaneously hypertensive rat (SHR). A significant number of compounds were found to display potent activity in one or both assays, and preliminary structure-activity relationships with respect to each assay were delineated. Compound 94, the 1,1-dioxide of [(6,7-dichloro-2-n-propylbenzo[b]thien-5-yl)oxy]acetic acid was markedly active in both the ASLM and SHR by oral administration. The combined diuretic/hypotensive profile of this compound was further substantiated by its good saluretic response in water loaded conscious dogs and a moderate to good activity in renal hypertensive rats and sinoaortic-deafferented hypertensive dogs.