OBJECTIVE: To describe the trends in the profile of blood donors from 1995 through 2001 at a large blood center in the city of São Paulo, Brazil, particularly following the initiation in 1998 of marketing strategies aimed at substituting replacement donors with altruistic repeat donors. METHODS: Using an information system that had been established at the Pro-Blood Foundation/Blood Center of São Paulo (Fundação Pró-Sangue/Hemocentro de São Paulo) in 1994, we collected information on sex, age, and type of donation for the years 1995-2001. We classified blood donors as either replacement blood donors (if they stated that the reason for donating was that they had a friend or relative in the hospital) or as altruistic donors. First-time blood donors were those who had not donated in our institution since the establishment of the information system. RESULTS: The percentage of repeat altruistic blood donors increased over time as first-time replacement donors declined for both genders. The proportion of altruistic donors climbed from 20% of all blood donors in 1995 to 57% in 2001. In 2001, first-time blood donors represented only 52% of all donors, as contrasted to 88% in 1995. Female donors increased from 20% to 37% of the donors over the period studied. CONCLUSIONS: Our data provide evidence that the São Paulo population has responded well to the marketing strategies that have been introduced in our institution. We believe that similar promotional efforts elsewhere in Brazil would produce comparable, positive results.