The study is one of the first prevalence studies of gambling and problem gambling among casino patrons in Macao. It aims to identify the demographic profile of gamblers and evaluate the extent of problem gambling among casino patrons. Using a convenience sampling approach, over 6,000 people were intercepted in the proximity of casinos and were invited to answer a structured questionnaire anonymously and voluntarily. Among these people 1,352 respondents indicated that they gambled in casinos at least once in the past 12 months. Over 90% (1,228) of the respondents reported that they gambled in Macao’s casinos and slot lounges. The three most popular forms of casino gambling were baccarat, Sic Bo, and slot machines. The monthly median expenditure on gambling was HKD 1,845 with a range from HKD 2 to HKD 375,175. The prevalence rates for problem gambling and pathological gambling were 15.1% and 7.1%, respectively. Implications of the study’s findings are given.