A proprietary whey growth factor extract (WGFE) or Lactermin (Lact milk; ermin growth factors) is a whey fraction of milk containing the major proteins lactoperoxidase and lactoferrin, together with a variety of minor proteins and peptides such as the growth factors IGF-I, IGF-II, PDGF, FGF, TGF-ss and betacellulin. This growth factor component of milk has been suggested to possess biological properties such as the promotion of tissue repair and anti-inflammatory activity. In this study the safety of Lactermin has been evaluated using genotoxicity assays (Ames, mouse lymphoma and micronucleus assay) and in a subchronic (13 week) rat oral toxicity study. In vitro Lactermin did not show any mutagenic properties in the Ames or mouse lymphoma assay and in vivo did not show any adverse clinical effects or in the bone marrow of male or female mice. In the subchronic oral toxicity study in which 10 rats per sex were fed Lactermin mixed with rat diet to deliver doses of 300, 1000 and 3000 mg/kg/day for 13 weeks, male and female rats did not show any test article-related clinical observations or effects on body weight, food consumption, ophthalmic effects, functional observational battery, organ weights, locomotor activity, hematology, serum chemistry, urinalysis or macroscopic or microscopic pathology. The results from the genotoxicity studies and the subchronic oral toxicity study suggest Lactermin is safe for consumption with a no-observed-adverse-effect level (NOAEL) of 3000 mg/kg/day.