Pelargonic acid and its esters function as skin-conditioning agents in cosmetics. Molecular weight (mw) and octanol-water partition coefficient data suggest that dermal penetration is possible. The biohandling of branched-chain fatty acids is not the same as for straight-chain fatty acids, but the differences are not significant to the conclusion that they all are readily metabolized to nontoxic moieties. Limited data suggested that the penetration of other ingredients may be enhanced if these ingredients are present in the same formulation. These ingredients are not significant oral or dermal toxicants in animal studies. They are not reproductive/developmental toxicants or genotoxic/carcinogenic in animal studies. The available data suggested that product formulations containing these ingredients would be nonirritating and nonsensitizing to human skin, but formulators were cautioned to consider the penetration enhancement potential. The Cosmetic Ingredient Review (CIR) Expert Panel concluded that these ingredients are safe in the present practices of use and concentration.