A new iontophoretic device was utilized in the treatment of hyperhidrosis axillaris (5 patients), hyperhidrosis manuum (12 patients) and hyperhidrosis pedum (10 patients). Unilateral treatment was carried out daily for 3 weeks. Degree of sweat inhibition was assessed quantitatively in relation to the untreated control side by means of hygrometry and also estimated by a colorimetric method. In 3 patients with palmar hyperhidrosis and in 2 patients with plantar hyperhidrosis sweating returned to normal levels, thus hyperhidrosis was completely curbed. A moderate reduction of sweat rates was induced in 4 patients on palms and in 3 patients on soles. In the remaining group sweat inhibition was only slight. In treatment of palmo-plantar hyperhidrosis side effects were minimal. Axillary hyperhidrosis was only moderately reduced in some patients. Skin irritation due to iontophoresis posed a problem.