Frozen sections (FS) are usually performed in a General Hospital and are very useful for the surgical procedure orientation. PURPOSE--To verify the accuracy of the FS performed at the Hospital de Clínicas de Porto Alegre (HCPA), RS, Brazil. METHOD--2,152 FS were carried out between March 1986-September 1991, in a prospective study. RESULTS--3.7% of the conventional pathologic examinations (58,127), performed in the same period, correspond to the FS examined. When the FS diagnosis differed from the definitive one (in paraffin) it was classified as False Positive (0.4%), False Negative (1.8%) or inconclusive (2.8%). The organs more frequently examined were lymph nodes (19.3%), ovary (17.21%), breast (16.6%) and thyroid gland (12.4%). We observed accuracy indices in 95% of the FS examined, and in 97.8% when excluding the inconclusive ones. CONCLUSION--The accuracy indices of FS performed in HCPA were similar to the ones found in the literature, which vary from 90.4% to 98.5%.