Menstrual underwear are reusable, leak-resistant menstrual hygiene products. Per- and polyfluoroalkyl substances (PFAS) are persistent anthropogenic chemicals that present health risks. We performed targeted liquid chromatography-mass spectrometry analysis on PFAS in methanol extracts of three menstrual underwear garments and one nonmenstrual organic cotton underwear as a control. Twenty PFAS were detected above the limits of quantitation in at least one layer of a garment. All layers of menstrual and nonmenstrual garments contained at least one target PFAS, with total target PFAS concentrations up to 1.69 ng PFAS/g fabric. Outer crotch layers, which contacts the epidermis, exhibited the highest total PFAS concentrations. The inner gusset, worn in contact with the genitals, also contained PFAS, suggesting a potential exposure route. Both short- and long-chain PFAS of various subclasses were among the layers, with fluorotelomers detected most frequently. These findings indicate that monomeric PFAS may be present in both menstrual and nonmenstrual underwear, a potential source of PFAS exposure for users, and contribute PFAS to domestic wastewater via laundering.