Perennial peanut species Arachis glabrata Benth. (rhizoma peanut) and A. pintoi Krap. et Greg. are promising forage legumes for the tropics. Seventy-seven accessions primarily of the rhizoma species and six A. pintoi were evaluated for adaptation, rate of plant spread, yield, nutritional quality, and persistence in small plots on an Oxisol at the USDA-ARS farm in Isabela, Puerto Rico. Single plant introductions exhibited significant variability in plant density and plant height one year after planting. Selected accessions of rhizoma peanut were evaluated for rate of plant spread, rhizome development, and forage yield. A full-plot cover of rhizoma peanut was obtained between 24 and 36 weeks after planting. Significant variability was detected for rhizome yield, which averaged 3.21 kg m- 2. Crude protein content (CPC) of rhizoma peanut ranged from 163 to I 97 g kg-I and in vitro dry matter digestibility (IVDMD) from 523 to 616 g kg- 1. Dry matter yield (DMY) averaged 1.44 t ha-I at 36 weeks of growth. Introduction plot material subjected to mob grazing was highly acceptable and persistent. Accumulative DMY of 2.2 t ha-I was obtained using 42-day grazing cycles on rhizoma peanut. A. pintoi accessions TARS 17182 and 17186 exhibited excellent plant spread with a full-plot cover at 16 weeks after planting. DMY of the two accessions averaged I.I t ha- 1, and averaged CPC and IVDMD of I 57 and 671 g kg-I, respectively. Generally, pests and diseases were not a major problem. Our findings indicate that these two perennial peanut species offer potential for use as protein banks, special purpose pastures, or in grass/legume associations in livestock production systems for the Caribbean region.