There is much evidence to suggest that the treatment of hypertension reduces the risk of cardiovascular diseases and that it is cost-effective in most patients. However, the effectiveness of treatment relies on compliance and maintenance of treatment. Each pharmacological agent differs in terms of side effects. The existence of side effects can result in poor compliance and switching between treatments. A number of studies have reported high discontinuation rates for anti-hypertensive therapies. This potentially imposes costs on the health service. The aim of this study is to use the MEDIPLUS data set to consider the cost arising from switching and discontinuation of therapy. The analysis will assess the resource costs in terms of extra GP visits and hospitalisations arising from individuals switching and discontinuing treatments. The total costs of hypertension were estimated to be around 76.5 m pound sterling per annum, of which 26.9 m pound sterling can be attributed to patients who switch or discontinue therapy.