Chamaecrista rotundifolia is a forage legume little used with Brazilian livestock; however, it has been studied for this purpose for over 40 years in Australia. The aim of this study was to characterize the influence of plant densities of approximately 444,400, 111,100 and 27,800 plants/ha (equivalent to spacings of 0.15 × 0.15; 0.30 × 0.30 and 0.60 × 0.60 m) on quantitative and qualitative parameters of C. rotundifolia grown in pure stands as forage under exclusive cropping for hay. While leaf dry matter yields in the first 93 days after planting ranged from 1.48 to 9.32 t DM/ha, declining to 0.71–4.92 t DM/ha in the subsequent 83 days, crude protein concentration of the material was only 7–8%. Since this species tends to lose leaf during periods of stress, larger paddock studies are needed to determine how well leaf material is retained under conventional hay-making conditions. Optimal stubble height following harvesting should be investigated in an endeavor to increase DM yields at second harvest along with improved survival of plants.