Hypogalactia has a relative high frequency in women having delivered preterm infants, who often have difficulties in maintaining a sufficient production of milk for their infants' needs over prolonged periods of time. Recent studies have shown a potential galactogogue effect of silymarin on milk production in animal models (cows and rats) and in humans (mothers of term newborns); nonetheless, none of the studies conducted on humans consisted of double-blind randomized clinical trials and no data are available concerning mothers who delivered preterm infants. The aim of our study was to assess the efficacy of silymarin (BIO-C®) as galactogogue and its tolerability in mothers who delivered preterm infants. We enrolled 50 mothers at 10±1 days post-partum who had delivered infants at ® and placebo arms. No adverse events were observed in the 2 arms among mothers and infants, and silymarin and its metabolites were not detectable in the analyzed human milk samples. Further investigation on specific patient groups affected by hypogalactia, defined according to stricter criteria, should be planned to assess the efficacy of the product in increasing milk production.