We surveyed physicians to determine what factors were associated with their reporting of impaired colleagues to Physician Health Programs (PHPs). We conducted a cross-sectional mail survey of 1000 randomly selected practicing physicians in the United States. A survey instrument asked the physicians whether they would report 10 hypothetical impaired colleagues to a PHP. The results show that a majority of the physicians would report physicians to PHPs, but were more likely to report hypothetical physicians involved in substance abuse than those who were emotionally or cognitively impaired (p<0.001). Respondents who felt they had a societal obligation as opposed to an obligation to protect the rights of the individual (p=0.006) were more likely to report hypothetical physicians. Those respondents who stated they knew of guidelines on reporting impaired physicians had more frequently reported impaired colleagues (p<0.001). We conclude that physicians should be educated on the availability and functioning of PHPs and the ethical and legal obligations of assisting impaired colleagues.