Cotton in the Arizona desert land has exhibited some large production fluctuations over the past three decades. Three detrending techniques were used to measure these production variations. Results revealed that Pima cotton production was more unstable than upland cotton production. The production variability of Pima cotton increased significantly between the two periods studied (1967-1978 and 1979-1990) while the production variability of upland cotton declined slightly. By further analyzing the two components of production, harvested acreage and per acre yield at both state and county levels, it was concluded that the uncertainty in Arizona cotton production was attributed to various market forces, biological factors, government farm programs, and divergences in regional climate.