A case-control study was carried out in the Metropolitan Region of São Paulo, Brazil, to determine the protection against tuberculous meningitis conferred by BCG vaccination to children aged less than 5 years. The BCG vaccination coverage in the study area was about 88%. A total of 72 tuberculous meningitis patients were studied as well as 505 neighbourhood and 81 hospital controls. Analysis of the data using a conditional logistic regression for matched case-control studies indicated that the efficacy of BCG was similar for both groups of controls, that for neighbourhood controls (84.5%) being slightly greater than that for hospital controls (80.2%). No significant interactions were found between vaccination status and sex, age, or socioeconomic status.