Three batches of feta cheese manufactured from raw (R) and thermized (TS) milk with yogurt as a starter were studied. Enterobacteriaceae and coliforms underwent a more accelerated decrease in TS cheese. Nonstarter lactic acid bacteria (NSLAB) were counted at higher levels in R than in TS cheese throughout ripening and predominated over the other microbial groups. The composition of NSLAB in the fresh cheese was similar for both cheese types. Proteolysis products (noncasein nitrogen soluble in 12% trichloroacetic acid, nitrogen soluble in 5% phosphotungstic acid /100 total nitrogen) were higher in R than TS cheese. Degradation of αs-casein was in R > TS, while a small reduction of β-casein during storage was recorded only for TS cheese.