BACKGROUND: The practice of naturopathy and Western herbal medicine (WHM) was built on traditional evidence but may be undergoing change with the advent of scientific evidence. The aims of this research were to provide a better understanding of practitioners' attitudes towards evidence, information sources, professional regulation and their knowledge about the evidence of commonly used complementary medicines (CMs). METHOD: Naturopaths and WHM practitioners were invited to participate in an anonymous, self-administered, on-line survey. Participants were recruited using the mailing lists and websites of CM manufacturers and professional associations. RESULTS: Four hundred and seventy nine practitioners participated; 95% currently in practice. The majority (99%) thought well documented traditional evidence was essential or important, 97% patient reports and feedback, 97% personal experience, 94% controlled randomised trials and 89% published case reports. Significantly more recent graduates (less than 5 years) rated randomised trials as essential compared to others. Most (82%) respondents want information sources containing both traditional and scientific evidence. They currently use several resources; 74% CM textbooks, 67% conferences/seminars, 57% CM journals, 48% databases and 40% manufacturers' information. The mean knowledge score was 61.5% with no significant differences between respondents with diploma or degree level education or by graduating year. Eighty-five percent of practitioners strongly agreed or agreed that practitioners should be formally registered to safeguard the public, 8% were unsure and 8% disagreed or strongly disagreed. CONCLUSION: Naturopaths and WHM practitioners accept the importance of scientific evidence whilst maintaining the importance and use of traditional evidence. The majority are in favour of professional registration.