Analysis of stable C, N isotopes from bone collagen was conducted in 10 skeletons from the Great Moravian burial site at Mikulčice-Kostelisko The skeletons contain the following range of stable nitrogen isotopes in their bone collagen ( 15N + 8.8 to 12.5 prom., with an average of 10.72 +- 1.17 prom.) and of stable carbon isotopes ( 13C -17.8 to -19.6 prom., with an average of -18.89 +- 0.5 prom.).