An informed consent and voluntary assent in biomedical research with adolescents is contingent on a variety of factors, including adolescent and parent perceptions of research risk, benefit, and decision-making autonomy. Thirty-seven adolescents with asthma and their parents evaluated a high or low aversion form of a pediatric asthma research vignette and provided an enrollment decision; their perceptions of family influence over the participation decision; and evaluations of risk, aversion, benefit, and burden of study procedures. Adolescents and their parents agreed on (...) research participation decisions 74% of the time, yet both claimed ultimate responsibility for the participation decision. Both rated most study procedures as significantly more aversive than risky. Parents were more likely to rate aspects of the hypothetical study as beneficial and to provide higher risk ratings for procedures. Disagreements concerning research participation decisions and decision-making autonomy have implications for the exercise of voluntary assent in biomedical research. (shrink)