Human glutamate carboxypeptidase II (GCPII; EC 3.4.17.21) is an established marker for prostate-cancer diagnosis as well as a candidate therapeutic target for the treatment of diverse pathologies that involve glutamatergic transmission. Structural data on GCPII are thus valuable for the design and optimization of GCPII-specific inhibitors and diagnostic probes. The currently available structure of ligand-free GCPII was refined to a resolution of 3.5 A. This work reports the structure of the protein refined to 1.65 A resolution, with crystallographic values of R = 0.207 and R(free) = 0.228. The new structure extends the resolution appreciably and the new model based on this data shows significant differences when compared with the previously published model.