© 2014 ACOTA. Aim: To examine time trends and factors associated with exposure to potentially inappropriate medications (PIMs) by the Beers Criteria. Methods: PIM consumption days accumulated from the pharmaceutical claims of 251305 Western Australians aged ≥65 years (1993-2005) and person follow-up times produced counts/rates. Logistic/Poisson regression generated odds/rate ratios. Results: A total of 187616 participants (74.7%) took ≥1 PIM (1993-2005), the cohort consuming 109415 PIM daily doses/1000 person-years. Annual exposure decreased from 45-47% to 40%, and annual consumption rate declined from 117836 to 90364 daily doses/1000 person-years. Temazepam had the highest exposures (>17000 daily doses/1000 person-years). Number of medications taken (OR 35.03; 95% CI 34.37-35.71 for ≥10 vs. 0-2 drugs), annual drug intake (2.08; 2.04-2.12 for highest vs. lowest quartile), and high-level residential aged care (1.96; 1.91-2.01) were most predictive of PIM exposure. Conclusions: PIM exposure remains high in older Western Australians. Our findings identify patients most at risk and medications to consider on Australia-specific PIM lists.