Since the early 1990's, pyrethroids have become less effective for control of the cotton bollworm Helicoverpa zea (Boddie). In the beginning it was noticeable by an increased number of "escapes" following application and cleanup of these bollworms began to require higher rates. During the 1996 and 1997 growing seasons, we were involved with several reported field failures: upon investigation however, we were able to explain most of these as being attributed to delayed initial applications (bollworms were 2 - 5 days old), misapplications with rates and/or water volumes, inadequate coverage, or weather events. In 1996, we began utilizing the adult moth vial test and found individuals that survived, indicating resistance was present in the South Carolina population. The number of resistant individuals captured increased in 1998 and our state had several reported field failures; larvae collected from these fields were reared to adults and treated using the adult vial test. These data confirmed an increased level of resistance at each collection site. Based on these findings, South Carolina cotton bollworm recommendations were revised to include the following: A.) in areas with previous resistance problems or high resistance potential (Southern part of cotton growing area), we recommend planting the maximum amount of transgenic (Bt) cotton. This eliminates early season (June) application for tobacco budworm Heliothis virescens (F.) and reduces the potential number of applications for bollworm (July-August); B.) use alternative chemistries on budworms in June in conventional cotton AND for bollworms in July for conventional and Bt cotton for initial applications. Following this, look at bollworm control and secondary pest problems to date; choose chemistry accordingly; and C.) if pyrethroid applications were used in July for cotton bollworm control (both conventional and Bt), watch populations carefully for potential resistance.