A clinical picture indistinguishable fro, but not therefore identical with, myasthenia gravis (ocular form) developed within 24 hours of a wasp sting. Because of the close temporal association of events, operative mechanisms may be either an immediate hypersensitivity reaction to some components of wasp venom or a direct toxic effect of these substances on acetylcholine synthesis, release, or degradation. Theoretical considerations from the literature and the lack of immunologic abnormalities in the patient suggest that the latter may be correct. Unique host conditions must have been present at the time of the sting, implying latent or subclinical myasthenia gravis.