Specific labeling requirements would depend on the product. In general, The Fair Packaging and Labeling Act (FPLA) directs the Federal Trade Commission (FTC) and the Food and Drug Administration (FDA) to issue regulations requiring that all "consumer commodities" be labeled to disclose net contents, identity of commodity, and name and place of business of the product's manufacturer, packer, or distributor. FDA administers the FPLA with respect to foods, drugs, cosmetics, and medical devices. The FTC administers the FPLA with respect to other "consumer commodities" that are consumed or expended in the household. As an example, regulations for cosmetic labeling are administered by FDA and can be found in Title 21 of the Code of Federal Regulations, part 701.12 and 701.3 There are exemptions to the labeling requirement that may apply to certain size products and therefore, may be applicable to free samples; however, the "free" status of the sample does not have a bearing on these exemptions. Attempting to qualify for an exemption to the labeling requirements can be complex, and a mistake could result in the product being considered misbranded under the Act. Thus, if you are not confident in proceeding independently, we would suggest retaining a qualified consultant or lawyer.