An analytical method developed for the determination of total methiocarb residues on grapes included initial extraction with acetonitrile, oxidation of residues to methiocarb sulfone with m-chloroperbenzoic acid, derivatization with methanesulfonyl chloride, and quantitation by sulfur pecific flame photometric gas chromatography. Grape juice, pomace, and wine were analyzed to determine the fate of methiocarb during vinification. Samples were also analyzed for the individual metabolites of methiocarb by using similar methods but omitting the oxidation step. Total residue on Pinot noir grapes treated 4 times at 4.5 kg /ha was 46 ppm 7 days after a handgun application and 7.4 ppm if the material was applied by airplane. Residues on White Riesling grapes treated with a concentrate sprayer at the same rate ranged from 12 to 19 ppm 7 days after last application. About 50-80% of the residue on fruit was removed from the vinification process with pomace and additional reductions occurred during the settling of juice. Total residue in wines made from grapes treated 7 days before harvest was 4.9 ppm in White Riesling wine and 4.6 ppm in Pinot noir wine which represented 26 and 13% of the initial residue on grapes.