Although effective communication improves the quality of the relationships between patients and medical clinicians, resulting in better outcomes for patients, little is known about how patients influence that communication. Using a controlled, repeated measures design we investigated the role that patient question-asking plays in shaping the communication behaviors of health care providers. Medical students participated in simulated medical consultations with confederate patients adopting different information-elicitation styles. We examined the effects of passive, neutral, and highly-assertive questioning on the quantity of information delivered. Passive patients, who asked no questions and avoided eye contact, received less information (95.4 +/- 27.4 discrete items) than neutral patients (122.6 +/- 33.0 items). Highly-assertive patients, who engaged in active question-asking, sustained eye contact and used positive body language received the most information (135.6 +/- 46.9 items). The greater quantity of information given to highly-assertive patients was not accounted for solely by answers to questions. The increased information delivery elicited by highly-assertive patients is especially important when considered in light of memory limitations.