Background: Measurement of the Quality of Life (QoL) of autistic adults is receiving increasing empirical attention. The World Health Organisation (WHO) QoL measure (WHOQoL-BREF) has been utilised in several studies. Autistic adults report significantly lower QoL compared to neurotypical adults across several domains. However, no studies have investigated the suitability of WHOQoL-BREF as a tool to measure the QoL of autistic adults. Methods: This study explored the validity and reliability of WHOQoL-BREF with a mixed methods approach. Quantitatively, structural validity was explored by an exploratory factor analysis of WHOQoL-BREF data from 352 autistic adults aged 18-80 years. Qualitatively, four discussion groups (n=20 autistic people) were conducted to explore the face validity of the items of WHOQoL-BREF. Results: The five factor structure was conceptually similar to the WHO formulation of QoL, with adequate to good internal consistency of domains; however, some items loaded in an unexpected way. The reasons for these unexpected loadings were explored in the transcripts from the discussion groups. Conclusions: The findings suggest that the WHOQoL-BREF has acceptable validity and reliability for use with autistic adults; however caution is needed when interpreting data from the social domain and some other items