Initial studies on the methodology of enumerating lactic acid bacteria (LAB) on grass and silage indicated that (a) varying the homogenisation time in a stomacher from 1 to 7 minutes did not effect LAB numbers, (b) MRS and Rogosa media gave similar LAB counts in silage and (c) anaerobic incubation of plates led to higher counts of LAB from silage compared to micro-aerophi1ic incubation, but similar counts from grass. A survey of LAB numbers on grass grown for silage showed pre- and post- harvest values of 3.1 x 105 colony forming units (CFU)/g (range 1.40 x 104 CFU/g to 1.3 x 107 CFU/g.) and 3.3 x 105 CFU/g (range 1.6 x 104 CFU/g to 5.9 x 10° CFU/g) respectively. The numbers recorded were not related to grass dry matter or water soluble carbohydrate (WSC) content or to specific weather conditions pre- harvest. From a random selection of colonies, lactobacilli accounted for 64*, leuconostoc 25*, and streptococci 7* - of these 54* were identified as homofermentative and 32* heterofermentative. Total LAB were highest on dead material at the base of the crop (2.5 x 107 CFU/g), intermediate on the lower stem and inflorescence and lowest on the leaf (6.0 x 104 CFU/g) and upper stem (2.0 x 105 CFU/g). Counts of LAB differed slightly across 6 grasses and one clover but were greater than 10® CFU/g in all cases. LAB numbers on various parts of a new harvester and mower ranged from 0 to 104 CFU/cm2. After continuous use these values generally increased, with 107/cm2 being recorded on the harvester chute. Where unwilted grass with 4 x 105 CFU/g to 9 x 10s CFU/g was ensiled in large scale farm silos, values of 5 x 108 CFU/g to 1 x 109 CFU/g were found after 48 hours.