This is part 1 of a 2-part paper on ethics and physician-industry relationships. Part 1 offers advice to individual physicians; part 2 gives recommendations to medical education providers and medical professional societies. Physicians and industry have a shared interest in advancing medical knowledge. Nonetheless, the primary ethic of the physician is to promote the patient's best interests, while the primary ethic of industry is to promote profitability. Although partnerships between physicians and industry can result in impressive medical advances, they also create opportunities for bias and can result in unfavorable public perceptions. Many physicians and physicians-in-training think they are impervious to commercial influence. However, recent studies show that accepting industry hospitality and gifts, even drug samples, can compromise judgment about medical information and subsequent decisions about patient care. It is up to the physician to judge whether a gift is acceptable. A very general guideline is that it is ethical to accept modest gifts that advance medical practice. It is clearly unethical to accept gifts or services that obligate the physician to reciprocate. Conflicts of interest can arise from other financial ties between physicians and industry, whether to outside companies or self-owned businesses. Such ties include honorariums for speaking or writing about a company's product, payment for participating in clinic-based research, and referrals to medical resources. All of these relationships have the potential to influence a physician's attitudes and practices. This paper explores the ethical quandaries involved and offers guidelines for ethical business relationships.