The aim of this study was to describe the milk-plasma ratio and relative infant dose of gabapentin in a breastfeeding mother and to determine the well-being of her exposed infant. The mother-infant pair was studied over a 24-hour dose interval at steady state. Gabapentin concentrations were quantified by high-performance liquid chromatography. Infant exposure was calculated as concentration in milk multiplied by an estimated milk production of 0.15 L/kg/d and normalized to the weight-adjusted maternal dose. The milk-plasma ratio was 0.86; the relative infant dose was 2.34%. The absolute infant dose was approximately 3% of the children's dose for gabapentin, and the infant plasma level of 0.4 mg/L was approximately 6% of the maternal plasma drug concentration. No adverse effects attributable to gabapentin were noted in the infant. In combination with a previously published report, these limited data support the prescription of gabapentin to a breastfeeding mother after a careful individual risk-benefit analysis.