PENAL FINES ARE CONSIDERED AS AN ADVANTAGEOUS SUBSTITUTE FOR MANY FORMS OF PUNISHMENT WHICH INVOLVE DEPRIVING THE OFFENDER OF HIS FREEDOM. THE THREE MOST IMPORTANT FINES SYSTEMS ARE DESCRIBED, TOGETHER WITH THEIR RELATIONSHIPS TO PRISON SENTENCES. FURTHER, THE EXCESSIVE APPLICATION OF ADMINISTRATIVE FINES IS DEALT WITH, AS WELL AS THE MUCH CRITICIZED USE OF PRISON SENTENCES AS A SUBSTITUTE. AMONG THEIR CONCLUSIONS, THE AUTHORS RECOMMEND THE INTRODUCTION OF THE DAY-FINE SYSTEM (WHICH IS BASED ON DETERMINING THE SERIOUSNESS OF THE FINE IN TERMS OF DAYS, EACH OF WHICH IS EQUIVALENT TO A FIXED SUM) TO THE LEGISLATION IN SPAIN TO REPLACE PRISON SENTENCES. ALSO RECOMMENDED IS A REDUCTION IN THE NUMBER OF ADMINISTRATIVE FINES. (AUTHOR ABSTRACT)...KAP