This research identifies possible indicators of risk of aggressivity in a general hospital psychiatric ward going beyond the analysis of the episode in itself. We suggest that behaviour can be strongly conditioned by the milieu (which is organised in a similar way to other hospital wards) especially since we have found that violence is not correlated with diagnosis. We have used the Overt Aggressivity Scale and our own Ward Atmosphere Evaluation Scale (currently under validation) in order to identify those features which increase or reduce the risk of violent episodes. Factorial analysis and the study of risk probability have enabled us to create a 12 point scale (from red alert to yellow calm) of the probability/possibility of violent episodes. the scale allows psychiatric staff to assess the risk of aggressivity and consequently to modify the management and organisation of the ward if necessary (including emotional and psychological attitudes of the staff).