Many factors are believed to effect mail survey response behaviour and therefore create both non-response and response biases. The impact of one such factor experimentally investigated in the present study is the sample members' level of interest in the survey topic. The study verifies the dramatic impact that sample members' interest in the topic can have on response rates; sample members were almost twice as likely to participate if the survey dealt with a higher-interest topic than if the topic were of less interest. The study also investigated other response behaviour. That is, relative to lower-interest respondents, higher-interest respondents were less likely to omit answers to specific questions, but did not differ significantly in the internal consistency of their responses, or in their speed of response. Specific recommendations are offered to help survey researchers address the survey biases associated with sample members' interest or disinterest in survey topics. For several decades researchers have been concerned with non-response and response biases in mail surveys (Suchman & McCandless 1940; Toops 1926). The present study examines the effect that sample members' interest in the apparent survey topic can have on both types of biases. After a brief overview of non-response and response biases, previous research regarding the role of topic interest will be reviewed and shown to be inadequate. Then the present study and its findings will be discussed followed by several recommendations for survey researchers.