Despite increased availability of online promotional tools for prescription drug marketers, evidence on online prescription drug promotion is far from settled or conclusive. We highlight ways in which online prescription drug promotion is similar to conventional broadcast and print advertising and ways in which it differs. We also highlight five key areas for future research: branded drug website influence on consumer knowledge and behavior, interactive features on branded drug websites, mobile viewing of branded websites and mobile advertisements, online promotion and non-US audiences, and social media and medication decisions.