Three groups of rats, 45 per group (25 male, 20 female), were each exposed six hours per day, five days per week for fourteen weeks to the vapors of MRD-87-086 at mean actual concentrations of 10.5 ppm (Group II), 25.5 ppm (Group III), or 76.0 ppm (Group IV). A similar group of rats (Group I) was exposed only to air and serve as a negative control group. The primary study groups, which were sacrificed during the fourteenth week of exposure, consisted of 10 rats/sex/group. Satellite groups of 5 males/group were also sacrificed during the fourteenth week for whole body perfusion fixation and preservation of nerve tissue. Recovery groups, which consisted of 10 rats/sex/group, were sacrificed four weeks after the end of the exposure period. Assays performed during the study included daily in-chamber group observations, weekly individual in-life observations and body weights, and monthly food and water consumption determinations. Ophthalmologic and neurological (modified Irwin Screen) examinations were performed prior to exposure initiation and monthly during the study. Terminal assays, performed at both Week 14 and recovery sacrifices, included urinalysis (qualitative and quantitative), hemotology, serum chemistry, cholinesterase, gross necropsy examination, organ weight, and histopathology evaluations. No rats in any of the groups died as a direct result of exposure to the material.