Blood pressure (BP) is a key determinant of cardiovascular health, but the pathways that underlie the regulation of human BP are incompletely understood. Key to the ultimate development of fully effective preventive and management strategies for high blood pressure, both at an individual and population level, will be a comprehensive understanding of the relevant biological pathways. Studies of environmental and genetic risk factors can inform this understanding, and current approaches recognise the importance of both. Recognised environmental determinants of BP include obesity, salt intake and excessive alcohol consumption. Familial aggregation of BP has long been recognised, and estimates of the heritability of systolic and diastolic BP have exceeded 50%. The identification of genes involved in BP regulation, by improving knowledge of the relevant biology, should facilitate advances in treatment and control of BP. The study designs employed in such studies need to account for the fact that BP is a complex trait. That is, it is caused by multiple genetic and environmental determinants that may interact in complex ways.