Several unintentional biases are inherent to all cotton variety testing programs. The relative influence of these potential biases vary with the specific experimental methods employed. The objective of this paper is to enumerate and discuss the effects of various inherent biases that are associated with methods used in the Arkansas Cotton Variety Testing Program. The biases include factors associated with seed and stand (stand quality differences due to variation in initial seed quality), variety-specific management (inputs that may differ among varieties due to plant maturity, plant height, and insect and herbicide resistance), and sampling and ginning (effects of ginning small samples on laboratory-sized gin to determine turn-out and fiber properties). Some varietal types are given a slight advantage over other types because of the specific methods used. Overall, the biases tend to cancel each other so that any one varietal type is not given a great advantage. However, when interpreting data from the Arkansas Cotton Variety Testing Program, these potential advantages should be considered.