Two greenhouse trials were conducted to determine the response of selected aquatic weed species to foliar applications of flumioxazin {2-[7-fluoro-3, 4-dihydro-3-oxo-4-(2-propynyl)-2H-1, 4-benzoxazin-6-yl]-4, 5, 6, 7-tetrahydro-1H-isoindole-1, 3 (2H)-dione} and carfentrazone-ethyl (a, 2-dichloro-5-[4-(difluoromethyl)-4, 5-dihydro-3-methyl-5-oxo-1H-1, 2, 4-triazol-1-yl]-4-fluorobenzenepropanoic acid, ethyl ester). In trial one, flumioxazin and carfentrazone-ethyl were evaluated on the emergent species alligatorweed (Alternanthera philoxeroides [Martius] Grisebach), creeping water primrose (Ludwigia grandiflora [M. Micheli] Greuter & Burdet ssp. hexapetala [Hook. & Arn.] Nesom & Kartesz), and parrotfeather (Myriophyllum aquaticum [Vell.] Verdc.). In trial two, flumioxazin was evaluated on the floating species giant salvinia (Salvinia molesta DS Mitchell) and water lettuce (Pistia stratiotes L.). In both trials flumioxazin was applied at 0, 34, 168, 302, and 437 g ai/ha, while carfentrazone-ethyl was applied only in the first trial at 0, 56, 112, and 224 g ai/ha. At 4 weeks after treatment (WAT), flumioxazin controlled alligatorweed, giant salvinia, and water lettuce at least 91% with rates of 168 g ai/ha or higher. Creeping water primrose and parrotfeather were controlled 73 to 81% with 437 g ai/ha. Calculated EC90 flumioxazin values were 35.6 g ai/ha for alligatorweed and 70.3 g ai/ha for water lettuce. Creeping water primrose, giant salvinia, and parrotfeather EC70 values were 120, 256, and 164 g ai/ha, respectively. Carfentrazone-ethyl did not control