Human γδT lymphocytes have potent anti-tumour efficacy in vitro and have some clinical efficacy against solid and haematological cancers. γδT cells of Vδ1+, Vδ2+ or Vδ1-/Vδ2- subsets expanded and purified from the blood of healthy donors or childhood cancer patients have distinct memory and activation phenotypes, and anti- tumour functions. Second generation chimeric antigen receptors (CARs) can enhance γδT cell anti-tumour efficacy but lead to on-target off-tumour toxicity. First generation co-stimulatory CARs also enhance anti-tumour cytotoxicity of γδT cells but avoid on-target off-tumour toxicity, suggesting a possible clinical approach to targeting a wide range of tumour associated antigens.