This study compares two of the most widely used statistical techniques for analyzing data obtained from [15O]H2O PET studies of brain function. The Friston method (SPM94) and the Worsley (Montreal) method were applied to a single data set of 33 subjects who were studied in a paradigm designed to evaluate memory for word lists. Neither of these methods emerged as either strikingly different or strikingly preferable, although the occasional differences may be important in some experiments. In general, the two methods were found to produce similar results in identifying brain regions active during long-term memory: frontal, parietal, cingulate, and cerebellar. Underlying assumptions of the two methods, as well as their strengths and weaknesses, are discussed.