Increased access to gambling is proving to be a great burden on the individuals who partake, their families and society in general. Despite growing evidence for the use of Cognitive-Behaviour Therapy (CBT) with problem gamblers, important questions remain unanswered regarding those individuals who do not respond to CBT. This paper compares gamblers who are considered 1) treatment completers, 2) drop-out following an initial assessment and, 3) drop-out after commencing treatment from a specialized CBT service. The results indicate a number of differences between the groups in regard to gambling severity and behaviour, demographic profile and variations in overall psychopathology.