Serum progranulin is decreased in frontotemporal dementia (FTD) patients with progranulin gene (PGRN) mutations. We investigate the utility of prospective serum screening as a surrogate diagnostic marker for progranulin mutations. A commercial ELISA was used to measure progranulin protein concentration in serum from 63 FTD patients and 32 normal controls, and DNA screening then performed. Four patients (2/17 behavioral variant, 2/8 corticobasal syndrome) had abnormally low progranulin levels with PGRN mutations confirmed on DNA testing. Surprisingly, elevated levels were found in 6/16 patients with progressive non-fluent aphasia, the significance of which is unclear. Serum testing is an accurate and cost effective means of predicting PGRN mutations.