Recent research has made it clear that problematic gambling is often accompanied by problematic alcohol use. Unfortunately, little is known about the nature of this association, especially as it relates to gambling treatment outcome. The purpose of this study is to explore the effect of current alcohol use level and previous substance abuse treatment on the symptoms of a large cohort of pathological gamblers as well as on their response to treatment for pathological gambling. The sample included 464 men and 301 women recruited at six gambling treatment programs in Minnesota. Gambling treatment patients were assessed on a number of gambling problem severity and related clinical variables using the Gambling Treatment Outcome Monitoring System (GAMTOMS). Patients with frequent alcohol use had greater gambling involvement at baseline than infrequent alcohol users. Patients with a previous history of substance abuse treatment had more severe psychosocial problems, ostensibly resulting from their gambling behavior, than patients without past substance abuse treatment. A MANOVA with repeated measures showed that neither pretreatment alcohol use, nor past substance abuse treatment exerted significant effects on gambling treatment outcome. While the level of pretreatment alcohol use and a history of substance abuse treatment are markers for greater gambling problem severity, treatment outcome for pathological gambling was not adversely impacted by these variables.