Analyses have shown significantly higher serum glutamate levels in prostate tumours with Gleason scores of ≥8 than ≤7 and in black men compared with white men in the USA. In this study, immunohistochemistry revealed weak expression of glutamate receptors in normal and hyperplastic glands, but high expression in primary and metastatic carcinomas. Furthermore, glutamate blockade decreased tumour cell proliferation, migration, and invasion, and increased levels of apoptosis.