Antipsychotic drugs are key treatment for the acute psychotic symptoms experienced by schizophrenic, schizoaffective disorder and schizophreniform disorder patients. In the last years, atypical antipsychotics having fewer side effects than conventional neuroleptics, have been introduced into clinical practice. There is not an agreement about what type of drugs should be used in an emergency situation (acute psychotic patient). The aim of this observational, prospective study was to evaluate the impact of a treatment regimen with the atypical antipsychotic drug, risperidone, as first line treatment in acute psychotic patients that requested an admission into the hospital. Effectiveness of risperidone treatment was measured by Positive and Negative Syndrome Scale (PANSS) agitation sub scale, Brief Psychotic Rating Scale and days of in-patient period. Aggressive behavior was rated using Staff Observation Aggression Scale (SOAS) and Visual Analogic Scale for agitation and anxiety. Safety was evaluated collecting elicited adverse events. Observational study - Risperidone, 3-6 mg per day, orally, during the study period (in-patient period for each patient).