Objective: An estimated 29% to 91% of HIV-infected patients use complementary and alternative medications (CAM). The objective was to identify the most commonly used CAM by HIV-infected patients and determine the prevalence of associated adverse events (AEs). Methods: A single-center, prospective, cross-sectional study was conducted from February to July 2007 via convenient sampling. Inclusion criteria were: HIV-positive adults and using at least one CAM in the prior 12 weeks. Patient information (including demographics, CAM use, concomitant medication use, CAM-related AEs, purchasing behavior) was obtained using self-administered questionnaire and personal interview techniques. This study was approved by the institution's IRB and informed consent was obtained prior to enrollment. Descriptive statistics were performed to evaluate trends and assess AE outcomes (SAS Version 9.0). Results: One hundred individuals participated in the survey, with a response rate of 71.9%. Subjects were 45.0(9.9) mean(SD) years, 70% male, 54% Black, 32% Caucasian, 8% Hispanic, and 2% Asian. Fifty-five percent had a current/previous AIDS diagnosis. Forty-eight different CAM were used, and 96% of respondents were taking concomitant antiretroviral medications. The most common CAM consumed were: cranberry juice (72%), vitamin C (37%), green tea (34%), and garlic (8%). Most respondents (87%) purchased herbal medications on their own, and mostly from the grocery store (56%). Sixty-four percent of respondents did not inform their providers about CAM use. Fifteen percent experienced AEs that were CAM-related. Nausea and vomiting (33%) were the most frequent AEs reported. Eighty-six percent of subjects experiencing AEs neither consulted their physicians nor stopped using CAM that were thought to cause the AE. Conclusion: HIV-infected patients frequently use CAM concomitantly with traditional antiretroviral medications. Physicians and pharmacists should document and provide adequate education/counseling regarding CAM, especially for HIV-infected patients, to prevent drug interactions and AEs. More studies are needed regarding CAM utilization, safety, and its economic impact.