Health and fitness centers are becoming increasingly aware of their importance in the realm of preventive health care. Many hospitals have begun to open and run fitness centers, a trend that seems very likely to continue. In a competitive environment, every center would desire to obtain maximum valid customer information at minimum cost, and this paper addresses this issue. The authors investigate the confluence of both appeal and researcher credibility on mail questionnaire response rates from a metropolitan membership of a large fitness center. Personal appeal with high researcher credibility was found to generate significantly higher response rate followed by the hybrid appeal with low researcher credibility.