Playing Texas Hold 'em Online Poker (THOP) is on the rise. However, there is relatively little research examining factors that contribute to problem gambling in poker players. The aim of this study was to extend the research findings of Hopley and Nicki (2010). The negative mood states of depression, anxiety and stress were found to be linked to problem gambling; yet, the contribution of each factor was not independently assessed. In addition, skill may be particularly important for poker players. Therefore, the effects of two potential contributing factors, yearly monetary earnings and locus of control, on problem gambling were investigated. Participants were self-selected online poker players (N = 62) who completed an online survey. Results revealed that participants played an average of 16 h per week. Furthermore, 11.5% of the sample was classified as problem gamblers according to the Canadian Problem Gambling Index. Problem gambling was uniquely predicted by time played, the negative emotion of stress, and locus of control.