In this study, the authors systematically review the literature on biotin efficacy in hair and nail growth (1). They reviewed databases. They found 18 reported cases of biotin use for hair and nail changes. In all cases, patients receiving biotin supplementation had an underlying pathology for poor hair or nail growth. All cases showed evidence of clinical improvement after receiving biotin. The authors conclude that though its use as a hair and nail growth supplement is prevalent, research demonstrating the efficacy of biotin is limited. In cases of acquired and inherited causes of biotin deficiency as well as pathologies, such as brittle nail syndrome or uncombable hair, biotin supplementation may be of benefit. However, they propose these cases are uncommon and that there is lack of sufficient evidence for supplementation in healthy individuals.