Background: Omaveloxolone is approved for Friedreich ataxia (FA) in patients aged ≥16 years. The majority of individuals with FA have symptom onset at age <25 years and approximately 25% have symptom onset at age 25-39 years, with FA affecting men and women with an equal distribution. Because a majority of women receiving approved omaveloxolone are of child-bearing potential, it is important to understand possible infant exposure through breast milk. Objective: To determine the relative estimated infant exposure of omaveloxolone through breast milk following a single dose of 150 mg in healthy lactating women. Methods: In this Phase 1, open-label study, healthy participants received a single oral dose (3×50-mg capsules) of omaveloxolone. Blood and breast milk samples were collected over 336 hours, including an in-clinic stay of 96 hours postdose, to determine plasma and breast milk pharmacokinetics parameters. Breast milk from both breasts was expressed using an electric pump at scheduled intervals, pooled, and analyzed for volume and drug concentration. Safety was monitored throughout the study. Results: The 12 participants were aged between 23 and 38 years, the majority were White (67%), and the mean BMI was 27.1 kg/m^2. Following oral administration, omaveloxolone was slowly excreted into breast milk, with a median Tmax,milk of 12.3 hours and a mean t1/2 of 74.8 hours, closely matching plasma values (Tmax 10.1 hours; t1/2 73.3 hours). Based on area under the concentration time curve, estimated daily infant dose was 0.00756 mg/kg/day and the relative infant dose (defined as [daily infant dose / maternal dose] * 100) was 0.372%. Overall, a total of 5 treatment-emergent adverse events (TEAEs), all of which were mild in severity, were reported in 4 of 12 participants (33.3%); none were considered to be related to study intervention. There were no deaths, serious TEAEs, or TEAEs leading to study discontinuation. Conclusions: The results indicate that after oral administration of a single dose of 150 mg omaveloxolone, breast milk–fed infants may be exposed to a small fraction (<1%) of the adult dose. The safety findings observed in this study are consistent with the known safety profile for omaveloxolone.