The objectives of this research are I) knowing about Good Corporate Governance's implementation at PT. Tarnbang Batubara Bukit Asam (Persero) Tbk, 2) knowing about financial performance of PTBA before and after GCG implementation, and 3) analyzing in order to know if there is varian after GCG implementation. Research finding has shown varian of PT. BA financial performance before and after GCG …