The objective was to analyse the chemistry composition and in vitro digestibility of corn plant and pasture silage elaborated in Argentine Humid Pampa. Corn silage with grain at the milk-, paste- and firmgrain stage and pasture silage were analysed during six years (1996-2001). Dry matter (n=757), in vitro digestibility of dry matter (n=776), crude protein (n=771), neutral detergent fibre with and without amylase (n=245 and n=106) and acid detergent fibre (n=656) were analysed. The influence of climate dates was studied. ANOVA was carried out with experimental model that included the feed effect and nested year effect within feeds utilizing the GLM and the LS means of SAS. Differences in dry matter between milkgrain corn silage and pastegrain corn silage (23.4 and 42.8) were observed. Dry matter in paste grain corn silage and pasture silage was similar (30,6 and 31.6). Acid detergent fibre (31.0 versus 35.0) and neutral detergent fibre with amylase (57.3) versus neutral detergent fibre without amylase (53.8) in milk-grain corn silage and pasture silage respectively were similar. There were differences in all the composition variables between paste-grain corn silage and pasture silage and between years. For in vitro dry matter digestibility, a year effect in the three stages of corn silage was found. In paste-grain corn silage and pasture silage year effects were observed, but no direct relation between these results and weather was not possible to determine, thus the analysis of silage quality is recommended for its correct use.