Native pastures are the most important source of feed for the livestock industry in St. Croix, U.S.V.I. One of the major constituents of these pastures is guinea qrass (Panicum maximum), found in well managed, properly stocked situations. To determine the dry matter production of this species, plots were established in existing swards located in different rainfall zones. The plots were cut periodically for a full year. Yields at each site varied according to rainfall: from 7,543 kg/ha in the driest location to 14,445 kg/ha in the wettest area. Before the plots were cut, the height of the grass was measured. Regression analysis was performed, and a strong relationship between height and dry matter yield was demonstrated. This failed to adequately predict hay yields due to uneven cutting heights and inefficient raking with large equipment. Care must be taken when using regression techniques to predict dry matter production.