Informal payments for health care services are common in many transition countries, including Russia. While the Russian government proclaims its policy goal of improving access to and quality of free-of-charge health services, it has approved regulations that give local authorities the right to provide services against payment. This paper reports the results of a population-based survey (n = 2001) examining the prevalence of the use of medical services for which people pay formally or informally in two regional capitals of different economic status. The purpose of the study was to reveal any differences in the forms of and reasons for payments between the two cities and between socio-economic groups. The results indicate that formal payments were more common in the capital of the wealthier region, Tyumen, while the prevalence of informal payments was higher in the capital of the poorer region, Lipetsk. Around 15% of respondents had made informal payments in the past 3 years. Being a female (OR = 1.57), having a chronic disease (OR = 1.62), being a pensioner (OR = 2.8) and being willing to pay for additional medical information (OR = 2.48) increased the probability of informal payments. The survey demonstrates that in Russia access to and quality of publicly funded health care services may be under serious threat due to the current unclear, non-transparent financial rules. The practice of informal payments exists along with the introduction of formal chargeable government services, which may hamper the government's efforts to enhance equality among health service users.