A study investigated the perceived source credibility of organizations that produce health messages. Manipulated versions of a health advertisement were generated to represent three types of organizational sources: a nonprofit source, a for-profit source, and a combination of for-profit and nonprofit sources. The advertisements were then produced as print, radio, and television messages. Magnitude estimation scales measured source credibility and message acceptance, while a questionnaire measured the behavioral intention of the 264 subjects. The results showed that the nonprofit source and the combination source were perceived as having significantly higher credibility than the for-profit source. The print version of the message also was perceived as more credible than the broadcast version of the advertisement. Though no correlation was found between source credibility and message acceptance, a significant correlation was found between source credibility and behavioral intentions, suggesting that a subject's stated behavioral intentions seemed to be affected by the credibility of the source. (References and tables of data are appended.) (Author/SRT)