Hypertension is prevalent, affecting approx 20--25% of the adult population in the Western world. Primary hypertension is a multifactorial, complex disorder where many genes and genetic variants are assumed to interact with environmental factors in order to produce the specific blood pressure level for a given individual. Family and twin studies show that between 30 and 60% of blood pressure variation is determined by genetic factors. Monogenic disorders of hypertension are rare and do not explain blood pressure variability in the population at large. Obvious candidate genes for the study of hypertension are those that encode components of a blood pressure regulating system targeted by an antihypertensive drug, or those that are involved in counter-regulatory systems. In this review, we give a brief pathophysiological background to hypertension and the rational behind utilizing SNP genotyping in the study of hypertension and the antihypertensive response to treatment. We also discuss some of the novel results of pharmacodynamic studies in antihypertensive treatment, an area in its infancy.