Although anxiety is commonly researched in autism, the focus has predominantly been on anxiety disorders and not upon general levels of anxiousness or trait anxiety. This review summarises research investigating trait anxiety in autism. Systematic searches yielded 1099 records, with 23 studies meeting inclusion criteria. Study participants were mainly males from Western countries, with no representation of older adults or individuals with intellectual disability. All articles used self-report questionnaire trait anxiety measures. Anxiety measure psychometric details were absent in most studies, with 21 using subjective measures that are not validated for use in autism. Results showed higher trait anxiety scores in autism versus control groups, and correlations between trait anxiety scores and other study outcomes.