A microwave-based device has been developed to treat axillary hyperhidrosis by selectively heating the interface between the skin and underlying fat in the axilla. This study was conducted to evaluate the efficacy and safety of microwave-based devices for axillary hyperhidrosis and osmidrosis in Asians. Eleven patients (8 females and 3 males, age range 20-52 years, mean age 37.6 years) with axillary hyperhidrosis or osmidrosis were enrolled, treated with the microwave-based device, and followed up for 7 months. Procedure efficacy, patient satisfaction, and treatment safety were assessed. The clinical records were reviewed and the patients were interviewed individually at follow-up visits or via telephone. Evaluation of sweating showed at least a 2-point drop or greater in hyperhidrosis disease severity scale (HDSS) in 83.3% subjects (10/12 axillae) as measured at the 7-month follow-up. Of 16 axillae with osmidrosis, 93.8% (15/16 axillae) showed good to excellent results. Histologic findings also showed destruction of eccrine and apocrine glands that were replaced with fibrosis. Regarding safety, altered sensation of arms developed in one case that resolved after 3 months. This novel microwave-based treatment appears to be effective and well tolerated for the treatment of axillary hyperhidrosis and osmidrosis in Asians.