11 month old Sbrinz cheeses (i) 49 of good quality and (ii) 52 showing in storage the secondary fermentation defect (increase in size and glassiness of eyes) obtained from wholesalers were examined. Photographs of cut surfaces of (i) and (ii) are included and analytical results presented. It was concluded that in (ii) cheeses propionic acid fermentation was largely responsible for the defect, which was evident from significant differences in contents of acetate, volatile fatty acids, propionic acid, total lactic acid and malate dehydrogenases between (i) and (ii), and that weak butyric acid fermentation simulated secondary fermentation in some of (ii). The findings with (i) and (ii) Sbrinz cheeses are discussed in relation to those with Emmental and Gruyere