Direct-to-consumer (DTC) prescription drug advertising is one of the fastest-growing advertising categories in the USA and has generated a great deal of controversy among policy makers, physicians and consumer advocates. Previous studies have demonstrated that consumers are generally aware of DTC advertising and that DTC advertising influences consumer behaviours. However, a relatively unexplored area of research is the process of how DTC advertising influences consumer behaviours and how various consumer demographic and predispositional variables moderate the procedure. This study examined three types of consumer behaviours induced by DTC drug ad exposure, using the FDA’s 1999 national survey data. The study found that exposure to DTC drug advertising was strongly related to ‘drug information seeking’, ‘thinking about communication with doctors’ and ‘actual communication with doctors’. Other factors, including prescription drug use, health conditions, control over healthcare, and various demographic variables were found to influence the behavioural outcomes. The small amount of increase in explanatory power of these variables suggested they were more likely to indirectly affect key behavioural variables through DTC drug ad exposure.