Cotton (Gossypium hirsutum L.) acres in Kansas are spread over a large portion of the state.  Studies conducted in 2003 and 2004 to evaluated end-trimming (ET) timing to determine when and if this time consuming operation could be performed prior to harvest without unduly influencing final lint yields.  If ET was prior to first open boll (FOB) [2003] or 50-60% open boll (50B) [2004], plot yields were inflated from 10-23%, due to increased boll number and lint yields from the first two feet adjacent to the alley. If ET was at FOB or later, plot yields were increased by six percent or less. Yield influence on final plot yield declines as ET is delayed until approximately 115 days after emergence.  Small plots should not be ET until FOB or later to avoid distortions of large magnitude in actual yields.  If an alley is included prior to FOB, another ET of two feet after FOB should alleviate the over-inflation.