The aim of the study was to relate the basic dimensions of personality formulated by the model of the big five factors with problematic Internet use in a sample of 411 Colombian youngsters, 18-28 years of age, attending three private universities. Online survey questionnaires were administered for: socio-demographics and Internet usage habits, the Big Five Inventory (John, Donahue and Kentle, 1991), to assess personality, and the Internet Addiction Test (Young, 1998), to determine the degree of use of the Internet (controlled, problematic or addictive). The results revealed that 9.7% of the sample has a problematic Internet use. Among them, the majority were male ( χ 2= 12.93, p= 0.01) and performing communication and leisure activities. The problematic use correlates positively with neuroticism and negatively with friendliness and responsibility. On the other hand, is not related to extraversion and openness to experience. Being female and the responsibility dimension are protective factors from problematic use, while neuroticism predicts it. In conclusion, the study data provides empirical evidence of the relationship between personality and problematic Internet use.