In this article the authors present population-level prevalence rates for 61 specific drug-related problems occurring in three State Medicaid programs (Maryland, Iowa, and Washington) from 1989 through 1996 and a fourth (Georgia) from 1994 through 1996. The findings represent the first application of a consistent drug utilization review (DUR) screener program to Medicaid data across States. The study finds major differences in DUR failure rates among the four States with the lowest rates in Georgia and the highest in Washington. Only Iowa showed any population-level reduction in DUR failure rates during the study period, however, rates for community-dwelling elderly fell in most States.