This study was conducted to evaluate the yield potential of six Stvlosanthes quianensis introductions planted monthly from February to July, 1989, under short- and long-day periods, and harvested at 60 and 120 days after an initial 180-day cutting. Across planting dates, CIAT 184 had the highest mean DFY and CPC (7,160 kg/ha and 9.7%, respectively) at the 180-day cutting. The highest DFY and CPC were those of the February planting. Across planting dates and at the 60-day cutting, CIAT 1283 had the highest DFY (2,194 kg/ha) while the CPC of the six Stylos remained relatively constant (12.2-13.0%). At the 120-day cutting, across planting dates, CIAT 184 had the highest DFY (5,064 kg/ha) with a mean CPC of 11.7%. A positive linear relation was observed between days to flower and DFY. Significant differences were obtained among Stylos for all planting dates in terms of IVDMD (60-day harvest) except June and July. Across planting dates, all Stylos were significantly superior to CIAT 15 and CIAT 136. Based on this preliminary study, the optimal time for planting Stylo in Puerto Rico appears to be February-March.