Public service deregulation is favoured for motivating providers to offer consumers better pricequality services. Consequently, consumers are enabled to make informed choices and choose for the best service provider. However, recent publications reveal that consumers are not capable of exercising optimal choice behaviour. Despite these concerns, evidence is lacking on the extent to which potentially vulnerable consumers make use of the core element of deregulation-switching health plans. This article is meant to study whether potentially vulnerable consumers do indeed switch less health plans in the deregulated Dutch health insurance market than regular consumers. In order to answer this question, we extract questionnaire data from the LISS panel, covering the years 2009-2012. A total of 16,779 health insurance consumers were included in the sample. The average response rate was 78%. Logistic regression results show that consumers being chronically ill, 60 and older, and without Internet access, do indeed switch less often. Intriguingly, nonworking consumers and those living equal to or below the poverty line, turn out to switch more often than regular consumers. As a result, we conclude that the vulnerable consumer in the Dutch health insurance market is described by the following characteristics: chronically ill, 60 and older, and without Internet access. This specific group tends to get locked-in and suffers disproportionately from suboptimal choice behaviour.