OBJECTIVES: To estimate the sound pressure levels in areas with heavy and with local traffic in the city of São Paulo and compare the data obtained with the thresholds established by the local law. METHODS: Twenty-eight points in roads with heavy and local traffic were chosen. The measurements were done Monday to Friday, 8 am to 5 pm, using a 2236 Mediator (Brüel & Kjaer) following the International Standard (ref. no. 1996/1982 1,2,3). Each point was measured a number of times to produce a standard error lower than 1 dB. RESULTS: The equivalent continuous A-weighted sound pressure level (Leq) for the roads with heavy traffic ranged from 70.88 to 80.18 dB(A), mean 75.88 dB(A) (95% CI: 74.49; 77.27) and the maximum peak (MaxP) ranged from 102.47 to 108.37 dB(C), mean 105.63 dB(C) (95% CI: 104.59; 106.68). For the roads with local traffic we observed: Leq from 50.82 to 66.88 dB(A), mean 61.11 dB(A) (95% CI: 57.97; 64.26) and MaxP 83.13 to 97.33 dB(C), mean 92.81 dB(C) (95% CI: 89.80; 95.82). There was a strong evidence, p < 0,001, in favour of the difference between the two types of traffic roads regarding the sound pressure levels. CONCLUSIONS: The Brazilian Standards establishes 50dB(A) and 70dB(A) as the maximum limits for environmental noise in residential and industrial areas, respectively. The results of this study indicate that the problem of urban noise in the city of Sao Paulo needs to be tackled urgently due to its important public health impact.