AIM: This review is an attempt to comprehensively identify and synthesize the literature concerning Internet gambling. METHOD: Nineteen electronic databases were searched with a variety of search terms, and reference lists from obtained articles were followed up. 272 articles specific to Internet gambling were identified, with slightly more than half from peer-reviewed academic journals. RESULTS: Internet gambling started in 1995 and expanded rapidly. In July 2007 there were 2,069 Internet gambling web sites owned by 436 different companies. Revenues have been estimated at about $12 billion in 2005 and $15.2 billion in 2006, around 4 - 6% of the worldwide gambling market. In many countries, no clear legislation exists or applies to online gambling. Widely divergent legislation exists in countries that have enacted legislation, from complete prohibition to complete legalisation. The actual number of people who currently gamble online has been estimated to be between 14-23 million, with between 28-35% of these being U.S. citizens, 49% being from the Asia-Pacific region, and 23% from Europe (with the U.K. accounting for 1/3). The prevalence of online gambling in the general population tends to be quite low, but growing. Little research exists on the characteristics of people who currently gamble on the Internet, but internet gamblers tend to be male, young and from a higher socio-economic background. Game preferences and play patters are also underresearched, but existing evidence suggests frequent play on multiple sites, with games ranging from casino games to betting and poker. A minority of 3-4% tends to gamble considerably more than the rest. Convenience and choice were major factors for chosing online gambling, as were anonymity and available bonuses. The extent of crime-related problems, both from the operator and the player side, is currently unclear. It seems clear that underage online gambling is a problem, although its magnitude is uncertain. There is good evidence that online gamblers are significantly more likely to be problem gamblers, although a causal relationship has not been established. There is a general lack of responsible gambling practices and safeguards that are more typically found in land-based venues. CONCLUSION: There is likely to be a continued strong revenue growth, particularly in the Asian market, with betting exchanges and 'skill games,' and with mobile gaming. The market is likely to consolidate. There is also likely to be greater regulation, along with increasing problem gambling rates and online counselling support.