The aim of this study was to evaluate the inclusion of molasses in garlic (Alium sativum) foliage silages and its effect on in vitro ruminal fermenta-tion parameters and gases production including methane (CH4) and carbon di-oxide (CO2). To this end, fermentation was carried out in 16 microsilos with the addition of molasses (T1 - garlic foliage 90%, ground maize 10%, molasses 0%; T2 - garlic foliage 85%, ground maize 10%, molasses 5%; T3 - garlic foli-age 80%, ground maize 10%, molasses 10%; T4 - garlic foliage 75%, ground maize 10%, molasses 15%; n = 4) for 50 days. Subsequently, fermenta-tion was carried out in microsilos using rumen fluid for nutritional evalua- tion. The inclusion of molasses affected protein, neutral detergent fibre (NDF), non-structural carbohydrates (NSC) and lactic acid contents, and pH (P < 0.05); protein and NDF decreased 22 and 12%, respectively, with the in-clusion of 15% of molasses, and pH was generally reduced after the addition of molasses to the experimental treatments. However, molasses increased the NSC content and in vitro dry matter digestibility. Regarding ruminal fermen-tation, no changes were recorded in the proportions of volatile fatty acids (P > 0.05), while the concentration of total volatile fatty acids increased with the addition of molasses (P < 0.05). Ammonia-N levels decreased with the inclu-sion of molasses (P < 0.05), while maximum gas production increased up to 48%. Similarly, methane production increased by 46% at the maximum dose of molasses addition (P < 0.05), but no changes were recorded in the CH4:CO2 ratio (P > 0.05). These results suggested that the addition of molasses to garlic foliage silages did not result in significant changes in ruminal fermentation pa- rameters such as volatile fat acid (VFA) levels. Therefore, garlic foliage silage can be applied without additional supplementation to reduce agricultural waste and as a non-conventional alternative in ruminant nutrition.