Reports on tests of two different collagen extraction methods to compare their effects on the amino acid composition and lipid content of the sample. Lipids were extracted from modern and archaeological bones at different steps in each of these collagen extraction procedures. The authors compared the delta¹³C values of the lipid material and the lipid- and non-lipid-extracted collagen, and examined the effect of sodium hydroxide treatment on the lipid content, the amino acid composition, and carbon isotope analysis of bone collagen. The authors concluded that sodium hydroxide is not sufficient to remove lipids from samples prior to carbon isotope analysis. Further, different collagen extraction protocols do result in varying amino acid composition of the end product, but this does not necessarily affect the overall delta¹³C.