Multifactorial diseases such as coronary heart disease, cancer, and osteoporosis are of increasing public health concern. Such diseases have a complex etiopathogenesis involving genetic and environmental factors and interactions between these factors. Nonhuman primates are uniquely suited as animal models for complex human diseases because of their close evolutionary relationship to humans. We present the rationale for using nonhuman primates as animal models in research designed to assess the genetic determinants of multifactorial diseases. Strategies and current approaches for the use of nonhuman primate models in genetic research on complex diseases are reviewed.