Man and the domesticated dog share most of their genes and live in the same environment. Many common diseases have similar pathophysiology and clinical presentation. The publication of the canine genome sequence in 2005 has made it possible to use dogs as models for human genetic diseases. In a current EU-financed research project 'Unravelling the molecular basis of common complex human disorders using the dog as a model system - LUPA', the genetic background of cardiovascular as well as immunological diseases and cancer are studied. The genetic studies are performed using genome-wide association mapping (GWAM) to identify genetic risk factors for complex diseases, a method which has been proven highly successful for identifying loci of several genetic diseases. In humans more than 500.000 single nucleotide polymorphisms, SNPs, must be genotyped for whole- genome association studies, while only around 30.000 SNPs are needed for a comparable study in dogs. The reason for this is that selective breeding has created dogs with great morphologic variation between breeds but extensive genetic homogeneity within breeds, i.e. long haplotypes and high linkage disequilibrium. Three cardiovascular projects are included. In the first, a thousand dogs are studied to form a database of normal values for cardiovascular variables, with special focus on blood pressure. The aim of this project is to relate hypertension in humans to possible comparable disorders in dogs. Two cardiac diseases are studied; dilated cardiomyopathy and myxomatous mitral valve disease. Identification of their genetic background could help in finding new diagnostic and therapeutic methods, which could be beneficial for humans as well as dogs.