The objective was to evaluate the effect of inclusion of acetic acid during the ensiling of sugarcane (Saccharum officinarum) on fermentation quality and nutritional value. The treatments consisted of sugarcane silages, variety (IAC 86-2480) additives with four inclusion levels of glacial acetic acid (1.5, 3.0, 4.5 and 6.0 % in natural matter) plus the control. A completely randomized design was used, being 5 treatments and 6 replicates. The glacial acetic acid showed a pH 2.9 (0,1M). There was a reduction of 0.07 units in the pH of the sugarcane silage for each 1% inclusion of acetic acid (P < 0.01). The N-NH3 concentration was not modified in the ensiled mass of the treatments, with a mean of 0.45% in dry matter (P =0.91). The averages of effluent losses were adjusted to the quadratic regression model with the application of acetic acid (P < 0.01). There was a reduction in the yeast population in the order of 0.44 log UFC/g of silage (P < 0.01). The addition of acetic acid in sugarcane silage reduces fermentative losses, the yeast population and improves the nutritional value in doses from 1.5% of natural matter.