The Mexico City Prospective Study is a blood-based cohort study involving follow-up of 150,000 adults (50,000 men and 100,000 women) who were aged at least 35 years when recruited in 1998 to 2004. The study ran in two urban districts in central and northeast Mexico City, which were selected due to their population of diverse, but settled, mix of long-term residents and recent migrants from the north and south of Mexico. All men and women aged at least 35, living in the area were eligible to participate in the study. At baseline, the mean age of the sample was 53 years, two-thirds were women, and one in seven participants had attended university or college.