Background: Despite considerable recent reductions in antimicrobial use, the UK gamebird industry continues to struggle with production diseases during the rearing season, necessitating significant antibiotic use. This observational study investigated the presence of genes conferring resistance to β-lactam antibiotics within industry-reared pheasants and red-legged partridges in the UK. Methods: DNA was extracted from 60 pooled caecal samples collected from gamebirds at routine postmortem examinations during the rearing season. Genes encoding extended-spectrum β-lactamases (ESBL) were detected by PCR and the corresponding alleles were determined. Results: Over half (53%) of the samples harboured genes encoding bla TEM resistance, with bla SHV identified in 20% of samples. The bla TEM gene was more common on sites with higher antibiotic use, whereas bla SHV was predominantly found in birds younger than 5 weeks. Genotyping of the identified resistance genes revealed the presence of bla TEM-1 , bla SHV-1 and bla SHV-11 alleles.Limitations: This was a small-scale study conducted at four sites in southern England. Conclusion: This is the first report of the presence of ESBL genes in gamebirds, highlighting the need for further research into antimicrobial resistance in UK gamebirds.