In order to assess the interaction of N management with plant growth regulation of cotton following corn, a 4x2x2 factorial combination of N rates, N application systems, and a new plant growth regulator (Pentia™, mepiquat pentaborate) was evaluated in 2003 and 2004 near Stoneville, MS. The objectives were to determine the interaction effects of N management and Pentia (PGR) on cotton yields in a cotton/corn rotation and evaluate end-of-season plant characteristics with respect to N management and PGR use. For both 2003 and 2004, optimum lint yields were achieved with 120 lb N/A. There was no response to PGR when averaged across other factors in 2003. However, at the lower N rate (60 lb N/acre), PGR reduced lint yields by 110 lb/A (8.3%) when averaged across application systems. The PGR applications in 2004, initiated at early bloom, reduced lint yields at all N levels and ranged from 6.7 to 10.0% with the greatest reduction a the lower N rate. Plant height and total nodes increased with increasing N rates. Pentia reduced plant height and total nodes along with the height:node ratio. The NACB was not different where the PGR was applied. Results from this study remained consistent with previous research to determine optimum N management. Rates above 120 lb N/acre were not justified even in conjunction with PGR. It was concluded that applications of Pentia were not successful for increasing yields especially in 2004. Adding the cost of application and cost of the product to lower yields, resulted in significant financial loss when applications were initiated at first bloom. However, in studies where PGR applications were initiated earlier, Pentia did show a positive response, especially at lower rates. With respect to cotton following corn in rotation, additional growth can be expected compared to continuous cotton that could require a PGR.