Some examples of Longquan greenware have been analysed by neutron activation analysis. Most sherds are from kiln excavations in Zhejiang province, and date from the Song, Yuan and Ming dynasties. The elements Ce, Yb, Hf and Ta are shown to be consistently high and suggest that a common clay was used over a long period. The iron content of the glaze is shown to decrease from the Song to the Ming dynasty, implying an improvement in the refiring of the glaze raw materials.