The aim of this study was to ascertain the possible differences in personality, psychopathology, and response to treatment in pathological gambling according to age. The sample, comprising 67 participants, was divided into three groups: 32.6% with ages ranging between 17 and 26 years, 31.3% between 27 and 43 years, and 35.8% over 44 years of age. The participants were administered the following tests, Minnesota Multiphasic Personality Inventory [MMPI; Hathaway, S.R. & McKinley, J.C. (1943, 1961). Cuestionario de personalidad MMPI. Madrid Seccion de Estudios de TEA ed. 1970, 1975], sensation-seeking questionnaire [SSS; Zuckerman, M. (1979). Sensation seeking; beyond the optimal level of arousal. Hillsdale, NJ: Lawrence Erlbaum Associates], and the Symptom Check List Revised [SCL-90-R; Derogatis, L.R. (1977). Symptom check list-90 revised. Administration scoring and procedures manual. Baltimore]. All underwent a group treatment programme that was carried out in the Pathological Gambling Unit at Ciutat Sanitaria i Universitaria de Bellvitge (CSUB), Teaching hospital, Barcelona, Spain. The findings show differences depending on age in the participants' personality and in psychopathology and in their response to treatment.