Hypoxia is a primary stimulus for angiogenesis, which is important for tumour proliferation and survival. The effects of hypoxia on parathyroid tumour cells, which may be important for parathyroid autotransplantation in patients, are however, not known. We therefore assessed the effects of hypoxia on gene expression in parathyroid adenoma cells from patients with primary hyperparathyoridism. Cell suspensions from human parathyroid adenomas (n=5) were cultured and after selection in low calcium containing media, some cells were incubated under normoxic (21% oxygen) and some hypoxic (1% oxygen) conditions, for 48 h. cDNA expression analysis using Human WG6_v3 Illumina expression bead chips was performed on RNA isolated from these paired normoxic and hypoxic parathyroid cells, and the results of selected genes confirmed and validated by qRT-PCR on up to eight other parathyroid adenoma cultures. In total 549 genes were up-regulated and 873 down-regulated (>1.5-fold change; P<0.05). Amongst the most highly up-regulated genes (greater than fivefold) were those involved in hypoxia (CA9, SLC2A1 and HIG2). Other genes whose expression was effected were those involved in oxidative phosphorylation (COX10 −1.60-fold, CYC1 −1.70-fold and subunits of NADH dehydrogenase −1.80-fold) and the glycolysis pathway (ALDOA +2.15-fold, GAPDH +2.80-fold and ENO1 +1.99-fold), which is consistent with data indicating that cells shift metabolic strategy of ATP production in hypoxic conditions. Cancer-associated genes linked with vascular endothelial growth factor (VEGF) angiogenesis such as MAP2K1, JUN, ETS1 and MMP9 were increased by +1.97, +2.22, +2.19 and +1.56-fold respectively, with P<0.05; and proliferation genes RASSF1 and CCND1 were up- and down-regulated by +1.95 and −2.04-fold respectively, P<0.05. These changes were validated in up to eight other parathyroid adenoma cultures. Thus, our data demonstrate that parathyroid adenomas, under hypoxic conditions, have expression of genes known to promote angiogenesis and proliferation. These results may have implications for parathyroid cell culture and parathyroid gland autotransplantation in patients.