Summary The effect of brining time and smoking on the free fatty acid content of Idiazabal cheese during ripening was examined. The main free fatty acids considered underwent at least some increase during the first stage of ripening before day 90 and tended to level off around a constant value towards the end of the ripening period. There were significant differences in free fatty acid levels during ripening among cheeses with different brining times and between smoked and unsmoked cheeses. Brining time and smoking exerted marked effects on lipolytic activity during cheese ripening, depending upon the free fatty acid involved and ripening time. In general, brining and smoking led to increases in free fatty acid levels at the end of the ripening period; the different behaviour of butyric acid may be due to a specific lipolytic activity.