A theoretical model of persistent gambling is described together with the results of two preliminary investigations focusing on poker machine play under ecologically valid conditions. The subjects (N=80), the majority of whom already had experience of playing, gambled with their own money (either with or without a small priming fee), 1) in a laboratory setting on a commercially available machine (Golden Goose) with a genuine opportunity to win and lose (heart rate and subjective measures of arousal were recorded) and 2) in a second study, played under direct observation in a real club setting (subjective arousal, illusion of control and persistence were recorded). The results provided some support for the components of the model, particularly the hypothesized relationship between arousal and persistence.