Changes in microbial flora during the cheese-making and maturation processes of Spanish mould-ripened Cabrales cheese have been studied. In the interior of the cheese lactic streptococci, mainlyStreptococcus lactis, predominated before and during salting (0–4 d);Str. lactisand lactic acid-utilizing yeasts during dryingroom ripening (5–15 d); moulds, mainlyPenicillium roqueforti, and lactobacilli, mainlyLactobacillus plantarum, predominated during cave-ripening (16–120 d). On the cheese surfaceStr. lactiswas the majority flora before and during salting;Str. lactis, micrococci and leuconostocs were the main microbial groups during drying-room ripening, and micrococci throughout cave-ripening. Coliforms and coagulase-positive staphylococci died off during the first month of maturation.