1. A rapid method for measuring the rate of dealkylation of organophosporus-inhibited enzymes is described. 2. The dealkylation rates have been measured for acetylcholinesterase inhibited by isopropyl, sec.-butyl, 1,2-dimethylpropyl, 1,2,2-trimethylpropyl and cyclohexyl methylphosphonofluoridate, and by di-isopropyl phosphorofluoridate; they are first-order under the conditions used.