An evaluation was conducted of the Zycom AGRIplan 600 cotton yield mapping system. The system was installed on producer's cotton pickers and used by the picker operators. The yield map data was compared to hand sampled yield estimates. The hand samples were gathered as two samples of 0.001 acre in order to provide a comparison of the variability of the sample estimates as well as the yield map data. The Zycom yield mapping system did show general trends in yield across the fields, but there was considerable scatter in the data. Comparing the average of yield points within an area of 10 m radius improved the yield estimates. The 95 percent confidence interval for the area averages ranged from 35-50 percent of the yield.