Familial and twin studies suggest the implication of a genetic factor in pathological gambling, but mainly assess probands through treatment settings or advertisements. The question raised here is: are parents of casino pathological gamblers using slot machines more affected with pathological gambling than nonpathological gamblers, all interviewed on site at the same casino? Three hundred and fifty-five casino gamblers on slot machines, which included 96 pathological gamblers, 116 problem gamblers, and 143 nonproblem gamblers, were recruited in situ at the largest casino in the Paris suburbs. We evaluated pathological gambling and two addictive disorders (alcohol dependence and tobacco consumption) in the gamblers and their 690 parents (through the proband). Familial aggregation of pathological gambling was confirmed, with a risk of 3.3 for being a pathological gambler when at least one of the parents has problematic gambling. No familial co-aggregation of pathological gambling with alcohol or tobacco dependence was observed. Pathological gambling is found in excess in the parents of pathological casino gamblers, in accordance with previous aggregation studies devoted to other types of gambling, and with studies recruiting gamblers in different settings.