A patient suffered recurrent episodes of aseptic lymphocytic meningitis for many years and then developed amyotrophic lateral sclerosis (ALS). Immune-complexes were deposited in the renal glomerular basement membrane and mesangia. The necropsy study revealed both lymphocytic meningitis and ALS. Study of the motor neurons with the electron microscope revealed proliferation of endoplasmic reticulum, small cytoplasmolytic areas and focal neurofibrillar accumulations in axons. Interwoven, serpentine 10-15 nm. tubules first appeared with ER proliferation and, presumably at a later stage, were sometimes present in large masses. These tubules might be virus material but virus cultures, including tissue culture, and animal inoculations have thus far been negative.