OBJECTIVES: The Drug Price Competition and Patent Term Restoration Act of 1984 (Waxman- Waxman Act - WHA) established a patent extension system that allows sponsors of new drugs (NDAs) and biologic applications (BLAs) approved by Food and Drug Administration (FDA) to recover part of the patent time dedicated to clinical trials and to the FDA drug review process. The maximum extension is 5 years and the effective patent life from approval to patent expiration cannot exceed 14 years. We assessed the characteristic of drugs and biologics that had a patent extension in the period 1984-2012 and examined the patent life timeline from clinical trials to regulatory review, and from marketing authorization to patent expiration (i.e. effective patent life). METHODS: Data were derived from the FDA, the US Patent and Trademark Office, and the US Federal Register. Descriptive analyses were performed. T-test was used to assess differences in averages. Significant level was set at 0.05. RESULTS: The USPTO listed 499 pharmaceuticals with patent extensions in the study period; 453 NDAs (90.8%), 38 BLAs (7.6%), and 9 vaccines (1.8%). Drug regulatory and patent information was available for 323 pharmaceuticals (287 NDA, 32 BLA and 4 vaccines). The average±stdev patent extension was 2.7±1.4 years (median= 2.2 years; 95% CI= 2.62.8). The extension was longer for vaccines (3.7±1.3 years) than for NDAs (2.7±1.4 years) and BLAs (2.4±1.5 years). The average clinical trials time was 5.9± 3.1 years, being similar for NDAs, BLAs and vaccines. The average FDA review time was 1.7±1.3 years (higher for vaccines 2.6±2.5 years). The average length of the effective patent life was 8.7±7.0 years without patent extensions and 11.7±6.8 years after the extensions. CONCLUSIONS: A large number of pharmaceuticals were granted patent extensions in the US. The WHA significantly increased the effective patent life of pharmaceuticals.