Areas of soreness and numbness developed in two patients who were being treated for hypertension. In one the pain was especially severe and accompanied by weakness of certain muscles; in both patients the neurological findings were characteristic of polyneuritis. Remission of these symptoms followed promptly after the use of hydralazine as part of the antihypertensive treatment was discontinued. The patients had been receiving 700 and 600 mg. of hydralazine, respectively, per day. These dosages are considered rather high, and the polyneuritic symptoms have occurred only in these two instances among 700 patients treated with hydralazine during a five-year period. A syndrome resembling lupus erythematosus has been seen in six instances. There was evidence that the two patients here discussed were predisposed to polyneuritis by a previous low dietary intake of pyridoxine. It is recommended that polyneuritis occurring under these conditions be treated by discontinuing the hydralazine therapy and administering pyridoxine.