Objectives: To understand the physical activity beliefs of infertile women, and their physical activity behavior before and during assisted reproductive technology (ART) treatment. Methods: Infertile women undergoing ART treatment completed a survey assessing their physical activity beliefs. In addition, the physical activity behavior of the participants was assessed via the Godin Leisure-Time Exercise Questionnaire. Results: The participants were significantly less physically active during the treatment period, with 80.1% reporting that they believed there would be a negative effect on the outcome of their treatment if they did not limit their physical activity. Conclusion: The present study showed that women's physical activity may decline during ART treatment because of the misconception that pursuing their pre-treatment physical activity routine would decrease their chance of conceiving. (C) 2009 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.