We retrospectively studied the usefulness of intraoperative cytology (IOC) and frozen section (FS) in the rapid diagnosis of 68 thyroid lesions. In 14 cases of papillary thyroid carcinoma, IOC correctly diagnosed 13 cases, while FS correctly diagnosed 11 cases. There was no significant difference in sensitivities, and both methods had similar specificities. In 21 cases of colloid nodule, IOC was slightly more sensitive than FS; IOC correctly diagnosed 16 cases, while FS correctly diagnosed 15 cases. However, the specificity of IOC was only 71%, but was 98% for FS. Of 17 follicular adenomas, FS diagnosed 16 as follicular neoplasms and misdiagnosed only 1 as a colloid nodule. By contrast, IOC misdiagnosed 9 follicular adenomas as colloid nodules, most of which were macrofollicular variants with abundant colloid. Of 11 follicular carcinomas, FS diagnosed all as follicular neoplasms, while IOC misdiagnosed 3 as colloid nodules. While IOC is not as accurate as FS in the diagnosis of colloid nodules and follicular neoplasms, it is highly sensitive and specific in the diagnoses of papillary carcinoma and performance of the technique is rapid and easy. In an intraoperative setting, IOC is a useful adjunct to FS in screening thyroid nodules for the presence of papillary carcinoma.