© 2016 Elsevier Inc. Objectives Impulsivity is a construct that is strongly associated with Gambling Disorder (GD). The main objectives in the present study are: 1) to explore the role of sex and age on impulsivity levels in GD patients; 2) to identify the relationship of the different impulsivity facets with comorbid psychopathology and other personality traits in GD patients; and (3) to assess whether impulsivity is a predictor for the severity of GD. Method The final sample consisted of 406 consecutive participants. All of them were seeking treatment for GD (88.4% male and 11.6% female) and completed the South Oaks Gambling Screen (SOGS), the UPPS-P Impulsive Behavior Scale, the Symptom Checklist (SCL-90-R), the Temperament and Character Inventory-R (TCI-R) as well as other clinical and psychopathological measures. Results Results show a negative linear trend between age and lower sensation seeking levels as well as lack of premeditation (the higher the age the lower the UPPS-P scores), and a positive linear trend between age and positive urgency (UR) (the higher the age the higher the UPPS-P score). However, no sex differences were found for the assessed impulsivity dimensions. Lack of perseverance was positively associated with obsessive–compulsive symptoms and harm avoidance trait, and negatively related to persistence and self-directedness traits. Positive UR and negative UR were positively correlated with general psychopathology and the total number of DSM-IV criteria, and negatively associated to the following personality traits: self-directedness and cooperativeness. Finally, only the sensation seeking and negative UR of the UPPS-P showed predictive capacity on the severity of the disorder (the higher the impulsivity scores the higher the illness severity). Conclusions These findings highlight the association between impulsivity traits (measured by the UPPS-P) and GD in a large and consecutively recruited clinical sample with GD, taking into account the variables sex and age.