There is a trend toward primary resection without prior colostomy in the surgical treatment of Hirschsprung's disease (HD) that renders evaluation of the initial pathologic specimen of utmost importance. To determine the accuracy of diagnostic methods for HD in routine practice, biopsies and resection specimens of all patients being evaluated for possible HD during a 3-year period were reviewed and correlated. Eighty patients underwent a total of 132 procedures related to the diagnosis or treatment of HD, including 93 intraoperative frozen-section (FS) evaluations. FS analysis was performed on 12 of the initial pathologic specimens, with concordance between the FS and permanent-section diagnoses in 67% of specimens. The concordance rate for all FS evaluations in patients with HD was 89%, which is substantially lower than the institutional rate for all patients. Pathologic diagnoses resulted in two patients receiving suboptimal surgical treatment. Both of these errors resulted from incorrect FS diagnoses on initial diagnostic specimens. In conclusion, there is a high rate of incorrect FS diagnoses in HD. It is obvious that if FS is being used as the initial diagnostic method, and primary reanastomosis is to be performed in the same procedure, an incorrect FS diagnosis has severe implications. FS as an initial diagnostic procedure for HD is not recommended.