The present study was carried out to evaluate the survival rate of four tropical legume seeds submitted to different periods of ruminal incubation simulated by in vitro and in situ fermentation. The species studied were butterfly pea, stylosanthes, archer and perennial soybean. Four Holstein dairy cows fistulated in rumen were used in the in situ stage. A completely randomized design was used, in a 4 × 6 factorial arrangement (four species, six treatment periods) in the in vitro stage, with four repetitions. A completely randomized block design, arranged in a 4 × 6 factorial scheme (four species × six incubation periods), was used in the in situ stage, with four repetitions. The seeds (50 units of only one species at each repetition) were placed in erlenmeyer flask (250 mL) and were put in a 10 × 15 cm nylon bag in the in vitro stage. The times of incubation were: 6, 12, 24, 48, 96 and 144 hours and the time zero was estimated in the laboratory. The results demonstrate that, when submitted to ruminal incubation, due to their hard and impermeable teguments, legume seeds presented high resistance potential, and, thus, greater chances of germinating after passage through the gastrointestinal tract of bovines, when defecated in pastures. However, stylosanthes are not recommended for insertion in bovine feeding for this purpose, because they do not resist ruminal digestion.