A study of azinphosmethyl and esfenvalerate runoff losses after application to sugarcane for control of the sugarcane borer was conducted on the St. Gabriel Research Station of the Louisiana State University Agricultural Center. In a 2nd study, leaf loads of these insecticides were determined. The 24-h LC50(27.8 μg/liter) of azinphosmethyl to bluegill was exceeded in 2 of the 9 runoff events that occurred during the study period, but because of expected dilution effects downstream from the site of application, only the concentration (261 μg/liter) that occurred in runoff 2 d after application was high enough to cause concern. The 24-h LC50(4,530 μg/liter) of azinphosmethyl to channel catfish fingerlings was not exceeded. The day 2 level of esfenvalerate (1.91 μg/liter) did not exceed sufficiently the 24-h LC50(0.42 μg/liter) of this insecticide with respect to bluegill to cause concern; the toxicity of the pyrethroid to channel catfish (2.35 μg/liter) was not surpassed. A reduced (two-thirds) rate application of esfenvalerate with acephate did not lead to concentrations of the pyrethroid in runoff higher than its toxicity to these fish species. The time to 50% disappearance (DT50) of azinphosmethyl leaf residues varied from 0.90 to 1.09 d, which was similar to the DT50(0.76 d) of the chemical in runoff. Esfenvalerate on leaves was longer lived (DT50= 2.46–4.46 d). These runoff and leaf residue data indicate that azinphosmethyl or esfenvalcrate applications to sugarcane should cause little concern for toxic effects on bluegill or channel catfish except possibly in the event of runoff within 2–3 d of application of the azinphosmethyl (possible bluegill toxic effects) or within 1 d of esfenvalerate application (possible toxicity to both fishes). Reduced rate applications would be of substantially less concern.