Research has demonstrated that prohexadione calcium (calcium salt of 3,5-dioxo-4-propionylcyclohexanecarboxylic acid) retards vegetative growth of peanut (Arachis hypogaea L.) and in some cases increases pod yield, the percentage of extra large kernels, market value ($/kg), and gross value ($/ha). Spray adjuvants such as crop oil concentrate and nitrogen solution most likely will be recommended for application with prohexadione calcium. However, efficacy of prohexadione calcium applied with adjuvants has not been conclusively determined. Twelve experiments were conducted in North Carolina and Virginia during 1997 and 1998 to determine peanut response to prohexadione calcium applied with crop oil concentrate, urea ammonium nitrate, or a mixture of these adjuvants. Applying prohexadione calcium with urea ammonium nitrate, either alone or with crop oil concentrate, increased row visibility and shorter main stems compared with nontreated peanut or prohexadione calcium applied with crop oil concentrate. Prohexadione calcium increased pod yield, the percentage of extra large kernels, and gross value of peanut in seven of 12 experiments regardless of adjuvant when compared with nontreated peanut. Pod yield, the percentage of extra large kernels, and gross value of peanut were not affected in the other experiments. Prohexadione calcium did not affect the percentage of total sound mature kernels, the percentage of other kernels, or market value in any of the experiments regardless of adjuvant.