Informal payments can be found across Europe, Africa, Asia and South America. Despite its hidden nature, they pose an important policy issue. Reported as being widespread, the true scale and scope of informal payment are unknown, and estimations differ among studies. We look at the Russian health care sector where the existence of informal payments has persisted for decades. We present the scale and scope of informal payments, as well as patterns of informal payments and their determinants. We discuss the reasons for discrepancies in estimations and implications for the ongoing reforms.