Ryegrass (153 g dry matter (DM) kg-1; 180 g water-soluble carbohydrates (WSC) kg-1 DM) was ensiled directly, and after inoculation with a commercial product containing Lactobacillus plantarum and Pediococcus acidilactici to provide 104, 106 or 108 organisms g-1. The effects of mincing and of adding glucose (20 g kg-1) were also investigated. Inoculation with homofermentative lactic acid bacteria stimulated a more efficient fermentation, rapid acidification and the production of silages with higher lactate and lower acetate contents than uninoculated silages: there was some reduction in proteolysis and a considerable decrease in deamination. There was no advantage in exceeding 106 organisms g-1, but the 104 level was insufficient. There was no advantage in ensiling minced rather than chopped material, except that proteolysis was reduced. The addition of glucose did not have a beneficial effect in this experiment.