In recent years instances of aggression by patients towards health workers appear to have become more frequent. In Spain, no scientific studies appears to have been performed so far on this question. We analyzed questionnaires on workplace aggression from a stratified sample of 1826 health professionals at 3 hospitals and 22 rural and urban Primary Care facilities located in the Northeast and East of Spain. We found 11% of health workers had been a victim of physical aggression, 5% on more than one occasion, while 64% had been exposed to threatening behaviour, intimidation or insults. About 34% had suffered threats and intimidation on at least one occasion, and 23.8% repeatedly. Over 35% had been subjected to insults on at least one occasion, and 24.3% repeatedly. In general the incidence was higher in large hospitals, with very high levels in services such as Accident and Emergency and Psychiatry.