Introduction: The objective was to review key articles and research studies on practices, preferences, and evaluation of on-line continuing education used by health care professionals. Methods: Data sources included searches of the "MEDLINE," "CINAHL," and "ERIC" databases (January 1990 to June 2004) and manual searches of the "Journal of Continuing Education in the Health Professions" and "the Journal of Continuing Education in Nursing." Articles included reviews and research studies focusing on the use of Internet CE by health care professionals. The articles were categorized according to intervention, subjects, study design, and key findings. Results: Seventeen articles were eligible and were reviewed. Although in-person CE remains the most frequent and most preferred format. Internet CE is gaining in popularity. Most participants who engage in on-line CE are satisfied with the experience and find it to be an effective learning format. Barriers to on-line CE include technical difficulties and lack of computer knowledge. Discussion: Although the Internet is an effective and satisfactory educational format, barriers to use of the Internet for CE still exist. Additional studies are needed to measure the impact of Internet CE on practice performance, reduce barriers to on-line CE, and identify appropriate theoretical frameworks for on-line learning.