This paper examines the individual financial risk of health care expenditures over time in urban China, using longitudinal health expenditure data from 2005 to 2007 in Kunshan City, Jiangsu Province, China. We find that the stochastic process of log total health care expenditures is well represented by the sum of an AR(3) process and a white noise process. Simulating this model, we find that the urban health insurance system protects enrollees from the risk of catastrophic health care expenditures by bearing the majority of the health care expenditures. However, out-of-pocket health care expenditures represents a considerable risk to an individual’s financial status.