Abstract: A series of novel 6-substituted-5-oxo-6H-pyrido[2,3-d]pyridazine-8-ylacetic acid and 7-substituted-8-oxo-7H-pyrido[2,3-d]pyridazine-5-ylacetic acid compounds have been prepared, including their C.sub.1 -C.sub.6 alkyl ester derivatives, as well as the base salts of said acids with pharmacologically acceptable cations. Typical member compounds include those acids wherein the ring substitutent is always attached to the available ring-nitrogen atom and is either a lower aralkyl group or a lower heteroaralkyl group. These compounds are useful in therapy as aldose reductase inhibitors for the control of certain chronic diabetic complications. Methods for preparing these compounds from known starting materials are provided.