Corn (Zea mays L) is an ideal crop for silage due to its high levels of fermentable carbohydrates, but its major limitation for use in livestock is its low crude protein concentration (CP). An alternative to increase CP in corn silage is through its association with annual legumes. This study involved intercropping two annual legumes, lablab (Lablab purpureus) cv. Rongai  and Sunn hemp (Crotalaria juncea), with two corn varieties [HR-ORO and Quality protein maize (QPM)] to measure their effects forage yield, botanical composition, CP, neutral and acid detergent fiber (NDF and ADF) and fermentation characteristics upon ensiling.  The experiment was conducted in the Experimental Substation at Isabela, University of Puerto Rico between September and December 2009. The experimental design was a split plot in a 2 x 3 factorial, the main plots were the corn varieties and intercropped legumes and corn in monoculture were subplots with four replicates. Weed incidence in the corn crop decreased (P<0.05) from 31.0 to 13.6% in the intercropped legumes, and at the same time forage yield increased from 8.2 in monoculture to 10 Mg ha^-1 with intercropped legumes. Dry matter percentage of the silage was higher (P<0.05) in monoculture (26.0%) than in association with lablab (24.3%), and CP silage increased from 9.5% (monoculture) to 10.6% (intercropped legumes). The overall neutral detergent fiber (NDF) in the silage was 53.56% with little effect of treatments on pH and organic acids, resulting in excellent silage fermentation. In summary, corn-legume intercropping increased both forage and CP of silage without affecting the fermentation process.