A method is outlined for accelerating ripening in Swedish semihard cheese by increasing the number of lactic starter bacteria present in the cheese without impairing characteristic texture and flavour. In addition to the normal starter inoculum, suitable lactic starter bacteria whose lactic-acid-producing activity had been greatly reduced by previous sublethal heat treatment, were added to the cheesemilk. When suspensions of streptococci and lactobacilli cultivated at a constant pH were heated at 59 and 69°C respectively acid production was retarded by 5–10 h, which was found to be sufficient for the cheese-making. Proteolysis was lowered only 10–30% by these heating temperatures. Bacterial cell suspensions, prepared by the methods outlined and added to the cheesemilk, were incorporated in cheese curd to extents depending on the amount added and the type of starter. The number in the final cheese could be increased to a maximum of 4–5 times that of control cheese. No adverse effect of the extra starter bacteria on pH, fat content and water content of cheeses 24-h old was observed. Proteolysis, measured as the increase in trichloroacetic acid and phosphotungstic acid (PTA)-soluble N, increased with increasing number of cells in the cheese. Organoleptic judgements showed a positive correlation (r = 0·81) between taste and PTA-soluble N, which in turn was influenced by the number of cells in the final cheeses.