Transmission of foodborne pathogens from ill food workers to diners in restaurants is an important cause of foodborne illness outbreaks. The U.S. Food and Drug Administration recommends that food workers with vomiting or diarrhea (symptoms of foodborne illness) be excluded from work. To understand the experiences and characteristics of workers who work while ill, workplace interviews were conducted with 491 food workers from 391 randomly selected restaurants in nine states that participated in the Environmental Health Specialists Network of the Centers for Disease Control and Prevention. Almost 60% of workers recalled working while ill at some time. Twenty percent of workers said that they had worked while ill with vomiting or diarrhea for at least one shift in the previous year. Factors significantly related to workers having said that they had worked while ill with vomiting or diarrhea were worker sex, job responsibilities, years of work experience, concerns about leaving coworkers short staffed, and concerns about job loss. These findings suggest that the decision to work while ill with vomiting or diarrhea is complex and multifactorial.