Phosphorus (P) and potassium (K) soil test calibration and correlation data were developed thirty to forty years ago for cotton grown in Louisiana. The goal of this research was to verify the accuracy of both our data and the P and K fertilizer recommendations that are based on these data. During a 6-yr. period, four P field trials were conducted on two soil types, and five K field trials were conducted on five soil types. In seven of the nine tests, LSU fertilizer recommendations were correct (78%). Responses to P or K fertilizer did not occur when soil test P or K was rated high or very high. For the two cases in which recommendations were incorrect, fertilizer addition did not increase yield, even though soil test results indicated that a response should occur. In general, the results of these trials suggest that the current P and K fertilizer recommendations for cotton are accurate.