OBJECTIVE: Aggression, suicidality and involuntary treatment constitute severe clinical problems in first-episode psychosis (FEP). Although there are studies on prevalence and clinical predictors of these conditions, little is known on the influence of psychopathology and neuropsychological dysfunction.METHOD: 152 FEP inpatients were prospectively assessed using the Brief Psychiatric Rating Scale (BPRS) and a neuropsychological examination covering the domains 'processing speed', 'concentration and attention', 'executive function', 'working memory', 'verbal memory', 'verbal comprehension', 'logical reasoning', 'global cognition', and 'general intelligence'. Clinical data were collected retrospectively in a structured file audit trial.RESULTS: Patients were aged 24.5±4.9years, and 112 (74%) were male. At admission, 13 (9%) patients presented with severe aggression, and 28 (18%) with severe suicidality. 31 patients (20%) received involuntary treatment. In multivariate analyses, aggression was predicted by BPRS-Excited Component (BPRS-EC; p=.001), suicidality was predicted by BPRS-EC (p=.013) and general intelligence (p=.016), and predictors for involuntary treatment were BPRS-EC (p=.001) and neuropsychological dysfunction in the domain 'concentration and attention' (p=.016).CONCLUSION: Psychopathology and neuropsychological functioning independently predict dangerous behavior in FEP patients. Some correlations with neuropsychology (e.g., of aggression with concentration/attention) are absent in multivariate analyses and may thus constitute a proxy of psychopathological features. In addition to clinical data, BPRS-EC can be used as a predictor of dangerous behavior. Patients with severe aggression and suicidality show different patterns of neuropsychological dysfunction, indicating that suicidality should not be conceptualized as subtype of aggressive behavior.