This study was to understand the gambling behavior among the Macau arrestees. The self-designed questionnaires and Gamblers Anonymous 20 Questions (GA20) were distributed to 168 inmates in Macau Prison in order to understand the following issues, 1) the prevalence of gambling behavior among arrestees; 2) the relationship between gambling behavior and crime commission; 3) the differences between males and females in their gambling participation. The study found that there were 76.20% (128 arrestees) of 168 inmates had not gambled before or without having any compulsive gambling problems, while there were 23.90% (40 arrestees) who were involved in gambling and had excessive gambling problems. Arrestees‟ crime commission related to their gambling behavior and they may be possible to commit instrumental crimes. Although money may play a vital role in the arrestees‟ crime commission with their gambling behavior, but this is only applicable in male arrestees for one of their reasons of continuous gambling and people with gambling behavior tend to commit instrumental crimes, while female arrestees may be likely to use gambling to reduce their life pressures. Moreover, it may be implicated to Macau prison that one of the reasons of committing crimes may be due to the gambling behavior and preventive treatment is essential for people with gambling behaviors. The thesis also provides further recommendations for future studies.