Recent highly publicized withdrawals of drugs from the market because of safety concerns raise the question of whether these events are random failures or part of a recurring pattern. The inverse benefit law, inspired by Hart's inverse care law, states that the ratio of benefits to harms among patients taking new drugs tends to vary inversely with how extensively the drugs are marketed. The law is manifested through 6 basic marketing strategies: reducing thresholds for diagnosing disease, relying on surrogate endpoints, exaggerating safety claims, exaggerating efficacy claims, creating new diseases, and encouraging unapproved uses. The inverse benefit law highlights the need for comparative effectiveness research and other reforms to improve evidence-based prescribing.