Thyroid scans using Na131I and 99mTcO4- in two (anterior and anterior oblique) projections were done simultaneously in 50 patients with single palpable nodule and in euthyroid state (nodular nontoxic goiter) and 20 normal subjects to evaluate the imaging ability of each radionuclide and the necessity of oblique view. In detection of a nodule as a cold or cool area, 99mTcO4- was slightly superior to 131I (82% to 78% with anterior view alone, 92% to 84% when oblique view is added in detectability), with addition of an oblique view, 5 more cold or cool area in 99mTc scan and 3 more 131I scan were detected. In normal subjects 99mTcO4- scan was significantly superior to 131I scan (90% to 70%) in getting normal pattern of tracer uptake in the glands. For routine imaging study of the thyroid, 99mTc pertechnetate scan with multiple projection is considered to be a preferable method.