The main aim of this investigation was to study the onset of violence in potentially violent patients with mental disorders. We tried to identify risk indicators associated with violent behavior in the short and medium term. We analyzed historical, social-demographic and clinical variables. We applied three assessment tools to a sample of 30 outpatients: an interview about violence risk factors; the Historical Clinical Risk Management Guide-20 HCR-20 (Webster, Douglas, Eaves y Hart, 1997); and The Overt Aggression Scale OAS (Yudofsky, Silver, Jackson, Endicott y Williams, 1986). The prevalence of threats and/or violent behavior was similar for the two studied periods: about 60%. A link of dynamic acute and static variables with violence was observed in the two first months, and mainly of the latter variables in the second period. Structured clinical risk tools are useful to perform risk assessment by professionals, but adding other variables can improve this predictive task.