The aim of this research was to determine the prevalence of sexual abuse in Spain and its long and short effects. A representative sample of Spanish society was studied (N = 1.821) through proportional stratified random sampling. Data were obtained by interview (Personal History of Sexual Abuse), carried out in the subjects home and by means of a Self Reporting Questionnaire (S.R.Q.), which the interviewer gave the subject to be returned by post. The results show a high prevalence of sexual abuse prior to age 17 (15% of males and 22% of females) with short-term effects (lack of trust, disgust, fear, hostility towards the aggressor, shame, anxiety, etc.) and in long-term a greater tendency towards mental health problems (F = 7.7; p < .01), as well as other problems throughout the life cycle (running away from home, school failure, sexual dissatisfaction, drug-taking, etc.). The high prevalence and the clear long and short effect make prevention programs and help for the victims advisable.