Bromhidrosis negatively affects quality of life, and many patients undergo surgery for treatment. Complete apocrine gland removal markedly reduces body malodor; however, few studies have objectively evaluated changes in apocrine secretions and the degrees of improvement after surgery. We aimed to evaluate these physiological changes in patients who were satisfied after surgery. Apocrine gland secretions contain many odorous fatty acids, including linear-saturated, linear-unsaturated, and branched-unsaturated C6-C11 acids. 1,2 Here, we measured (E)-3-methyl-2-hexenoic acid (3M2H), 3-methyl-3-hydroxyhexanoic acid (HMHA), and 3-methyl-3-sulfanylhexan-1-ol (3M3SH) using liquid chromatography–mass spectrometry (LC–MS/MS). Especially, the 3M2H, a C7 branched unsaturated fatty acid is found in human apocrine gland secretions that has a particularly strong stench, especially in Caucasians and Asians.