Cotton has two cotyledons. How necessary are they for crop performance? The purpose of these experiments was to determine what effect partial or complete loss of cotyledons in upland cotton has on selected agronomic and fiber traits. Experiments (RCB design, four replications) were conducted in 2000-2003 using ‘PM 330' in the field at Perkins, OK, on a Teller loam (a fine-loamy, mixed, active, thermic Udic Argiustoll). Shortly after emergence, cotyledons were partially or completely removed with scissors. Treatments included 0, 25, 50, (a different) 50, 75, and 100% cotyledon removal. The 2001 experiment was clipped slightly later than the others (i.e., when the first “true” leaf was about the size of a dime), and there were no significant differences among treatments for any trait. In the other experiments, 75% removal caused a 32-33% lint yield loss in 2 of 3 yr; and 100% removal caused an 81-100% yield loss all 3 yr. Complete removal of the cotyledons caused losses in 2 of 3 yr for picked lint percentage, pulled lint percentage, boll size, and micronaire and in 1 of 3 yr for fiber strength and elongation. Fiber length and uniformity ratio were not influenced by cotyledon removal. Apparently, cotyledon loss between 50 and 75% triggers losses in lint yield and losses between 75 and 100% does likewise for a number of other traits.