The purpose of this study was to evaluate the prevalence of high-risk smoking practices in a homeless population. High-risk cigarette smoking practices include misuse of tobacco products or alternative methods of cigarette smoking that increase the likelihood of ingestion of toxic substances and infectious agents that can potentiate the hazards associated with cigarette smoking. An 84-item questionnaire was developed by the researcher to measure these practices. Fifty-six male and three female homeless people were interviewed in downtown Los Angeles. The most common high-risk smoking practices were cigarette sharing (86%); smoking cigarettes remade from discarded cigarette butts and filters (71%); smoking cigarettes remade by others (63%); smoking discarded cigarette butts (63%); blocking filter vents (24%); using things other than tobacco, such as discarded cigarette filters and drugs, in remaking cigarettes (22%); and smoking discarded cigarette filters (19%). These high-risk smoking practices pose a greater risk of exposure to toxins trapped in filters and tobacco remains and increase the threat of infectious disease transmission. The long-term effects of high-risk smoking practices among the homeless have potential economic implications for society.