Uncoupling protein 3 (UCP3) dissipates energy as heat in human skeletal muscle, thus enhancing energy expenditure and affecting body mass. UCP3 has been associated with insulin resistance, obesity, sleeping metabolic rate, and transmitochondrial membrane transport of fatty acid anions. Factors affecting UCP3 gene‐expression include fatty acids and GLUT4 content (up‐regulation) and endurance exercise (equivocal reports). Fatty acid‐induced up‐regulation of UCP3 is most prominent in glycolytic fibers, whereas endurance training down‐regulates UCP3 in slow fibers. A direct comparison between muscle fiber type and UCP3 protein expression in human muscle is essential to explore the physiological role of UCP3 further. We combined immunofluorescence with conventional fiber typing to study concurrently fiber type and UCP3 expression in human vastus lateralis muscle of healthy controls and type 2 diabetics. Here, we report for the first time that, in controls, as in diabetics, UCP3 protein expression is most abundant in type 2b fibers, less in type 2a fibers, and only moderately expressed in type 1 fibers. Of the potential roles of UCP3 or factors regulating UCP3 expression, only a role of UCP3 in preventing oxidative stress completely matches the reported fiber‐type specific UCP3 expression. UCP3‐induced dissipation of energy may therefore serve multiple fiber‐type specific goals.