Surfactant toxicity was examined following application of octylphenol and linear alcohol surfactants to the adaxial surface of 10-day-old cowpea [Vigna unguiculata (L.) Walp. subsp. unguiculata ‘Dixielee’] leaves. Leaf damage first appeared as isolated discolored areas at the periphery of the droplet area, developed toward the center, and, when most severe, the entire droplet area was necrotic. Epidermal cells beneath the droplet area became discolored, lost structural integrity and collapsed. Similar changes were observed in the palisade layer and spongy parenchyma. In addition, walls of damaged cells were preferentially stained with Safranin O. For a given surfactant dose, phytotoxicity increased with increasing concentration, droplet volume, and temperature and decreased with increasing humidity. In general, phytotoxicity was inversely related to the length of the ethoxy (EO) chain for both the octylphenol (Triton X) and C12-15 linear alcohol (Neodol 25) surfactant series. Tissue did not recover after injury. Chemical names used: octylphenoxypoly(ethoxy)ethanol (Triton X-100), linear alcohol ethoxylate (Neodol 25-9).