Hyperhidrosis is an invalidating condition, and one that is difficult to treat. It is characterized by an excessive and uncontrolled production of sweat by the sweat glands, often causing psychological, social, and occupational problems for the patient. Hyperhidrosis can be distinguished in two forms: idiopathic (of unknown etiology), or secondary, due to an alteration of the endocrine system (ex: hyperthyroidism, neuropathy, neoplasia etc.) It is found in about 0.3-0.5% of the population and can be localized (axillary, palmar, plantar, facial) or diffused. The subcutaneous injection of type A botulinum toxin, until now used only for the treatment of blepharospasm or hemifacial spasm, has shown to be a useful treatment for localized hyperhidrosis. The objective of the authors is to evaluate the therapeutic efficacy, safety, and management of botulinum toxin treatment in patients affected with axillary or palmar hyperhidrosis resistant to conventional therapies.