Phosphorus (P₂O₅) and potassium (K₂O) fertilization information for conventional- (CT) and no-tillage (NT) cotton (Gossypium hirsutum L.) production systems is limited. Research was initiated in 1994 and continued through 1998 on a Loring silt loam at the Milan Experiment Station evaluating P₂O₅ and K₂O fertilization rates for CT and NT systems. The initial Mehlich I extractable P and K levels were low and medium, respectively. Experimental design was a split plot with tillage the main plot and P₂O₅- K₂O rates the sub-plots. The fertilization rates included 0, 40, 80, and 120 lb P₂O₅/acre with 0, 30, and 60 lb K₂O/acre, a total of 12 treatments replicated four times. These rates were broadcast before planting using triple-superphosphate and potassium chloride. N was applied at 80 lb/acre after planting using ammonium nitrate. D&PL 50 was planted 1995 and 1996 with D&PL 5409 planted 1997 and 1998. The ANOVA showed a tillage-by-P-fertilization-by- year interaction effect on yields. The data will be presented by tillage system. Yearly CT and NT yields were increased by P₂O₅ fertilization. Surface broadcasting 40 lb P₂O₅/acre was sufficient for increasing CT and NT yields for three of the five years. The 1995 and 1997 CT yields were increased with 80 lb P₂O₅/acre while the 1997 and 1998 NT yields were increased with 120 and 80 lb P₂O₅/acre, respectively. The 1998 yield increased with P₂O₅ fertilization were expressed by: Y (CT) = 1155.2838 + 4.104 P₂O₅ - 0.0234 (P₂O₅)² and Y (NT)= 10007.5863 + 6.3006 P₂O₅ - 0.0363 (P₂O₅)². Broadcasting 60 lb K₂O/acre increased CT yields three of the five years while NT yield were increased two years of the five years from broadcasting 30 lb K₂O/acre. For the other years, yields were unaffected by K fertilization.