The interaction of nitrogen (N) management with Pentia™ (mepiquat pentaborate) plant growth regulator (PGR) for cotton following corn was evaluated in a 4x2x2 factorial experiment. Four N rates, applied in two different systems, were evaluated from 2003 to 2005 with and without Pentia PGR near Stoneville, MS. The objectives of the study were to determine the interaction effects of N management and Pentia on cotton yields in a cotton/corn rotation and evaluate end-of-season plant characteristics. In both 2003 and 2004, optimum lint yields were achieved with 134 kg N ha-1 while optimum yields were achieved with 168 kg N ha-1 in 2005. There was no response to Pentia when averaged across other factors in 2003. However, at the lower N rate (67 kg N ha-1), Pentia reduced lint yields by 123 kg ha-1 (8.3%) when averaged across application systems. In 2004, with PGR applications initiated at early bloom, lint yields were reduced at all N levels and ranged from 6.7 to 10.0% with the greatest reduction at the lower N rate. For 2005, PGR application rates were reduced and the initial application made at pin-head square (PHS). This change was made in an effort to reduce yield loss and was supported by evidence from other studies that suggested applications initiated near bloom had no effect on or reduced yield. Lint yield increases with the PGR in 2005 ranged from 6.1 to 9.2% higher when averaged across N application systems. Plant height and total nodes increased with increasing N rates . Pentia reduced plant height and total nodes along with the height:node ratio in both 2003 and 2004. Plant heights were again reduced in 2005 but the extent of the reduction was less than observed earlier.