Nitrogen (N) management for cotton following corn was evaluated with PentiaJ (mepiquat pentaborate) plant regulator (PGR). Four N rates, applied in two systems, were studied with and without Pentia at Stoneville, MS.  Objectives determined the interaction effects of N management and PGR on yields from a cotton/corn rotation and evaluated end-of-season plant characteristics.  In 2003 and 2004, lint yields were optimized with 134 kg N ha^-1 while optimum yields were achieved with 168 kg N ha^-1 in 2005.  No significant increase above 67 kg N ha^-1 was measured in 2006.  Pentia application in 2003, when averaged across N management, resulted in no lint yield increase.  At the 67 kg N ha^-1 rate, Pentia reduced yields by 123 kg ha^-1 (8.3%) when averaged across N systems.  In 2004, with Pentia applications initiated at first bloom (FB), lint yields were reduced at all N levels and ranged from 6.7 to 10.0% with greater reduction at the lower N rate.  For 2005 and 2006, PGR application rates were reduced and initial application moved to pin-head square (PHS).  Lint yield increases with PGR in 2005 ranged from 6.1 to 9.2% depending on N rate. A similar response was observed in 2006 where increased yields ranged from 5.2 to 8.5% with the highest response at 134 kg N ha^-1.  Plant height and nodes increased with increasing N rates. Pentia reduced plant height, total nodes, and height:node ratio.  Plant height reduction has been related to PGR rates and timing of application.  In general, N rates above 134 kg N ha^-1 were not required for optimum yields especially when PGR applications were delayed until FB.  After four years and quite diverse climatic conditions, cotton lint yield increases have been observed when mepiquat pentaborate applications were initiated at PHS.  Delays until FB and higher PGR rates reduced yields.