Direct-to-consumer advertising (DTCA) of prescription drugs is allowed currently only in the United States and New Zealand. Promotional spending on DTCA has grown from $2.5 billion in 2000 to $4.5 billion in 2009. DTCA has been an issue of intense debate since the early years of its existence (Hoek, Gendall, and Feetham 2001; Royne and Myers 2008; Pol and Bakker 2010). Therefore, DTCA is undoubtedly an important topic that deserves researchers’ sincere attention (Farris and Wilkie 2005; Gellad and Lyles 2007). The research on DTCA has grown in a fragmented manner across several disciplines such as marketing, communication, public health, pharmacy, economics, medicine, and so on. There has been little to no effort to bring together these diverse bodies of literature and identify critical research trends and themes that would bring a holistic understanding to this intriguing body of research and show the way to future researchers to explore further in this area. Research on DTCA has been described as lacking in empirical content, rigorous methodology, comprehensive model building, and cause-effect studies. This study aims to review studies on DTCA with the aim of exploring the past and current trends in research, offering a comprehensive and inclusive definition of DTCA, identifying key themes on DTCA research, and providing potential agenda for future research.