The Taiwanese health insurance industry is just over 30 years old. Originally private and domestic, the industry underwent substantial institutional changes when it opened to foreign competition between 1987 and 1994 and when the Taiwanese government established national health insurance (NHI) coverage in 1995. Congruent with these changes, rapid growth occurred in the Taiwanese demand for private health insurance. In order to better understand the recent performance of the Taiwanese health insurance industry, the structure of the NHI system is described and then household decisions to purchase private health insurance are analyzed using a two-part (hurdle) model on 1998 Survey of Family Income and Expenditure data. Logistic and OLS regressions are used to examine the factors influencing the probability and amount of private health insurance purchased. Generally, factors affecting the probability of having insurance also influence the amount of insurance coverage purchased. Higher income and education levels are associated with increased probabilities and larger quantities of private insurance purchases. Married females, the employed, and household heads working in state-run enterprises are more likely to purchase private insurance than their counterparts. The probability of private insurance purchases varies by region, with northern Taiwanese households having higher odds of owning private insurance than non-northern households. Compared to those in rural villages, households in cities and towns are more likely to have private insurance. The likelihood of private insurance purchase also tends to rise with advancing age and larger family sizes. In addition, one important implication in the private health insurance market is highlighted. There is no complementarity between the public and private systems.