The aim of this study was to systematically review the psychometric properties, interpretability and feasibility of self-report pain intensity measures for children and adolescents for use in clinical trials evaluating pain treatments. Databases were searched for self-report measures of single-item ratings of pain intensity for children aged 3-18 years. A total of 34 single-item self-report measures were found. The measures' psychometric properties, interpretability and feasibility, were evaluated independently by two investigators according to a set of psychometric criteria. Six single-item measures met the a priori criteria and were included in the final analysis. While these six scales were determined as psychometrically sound and show evidence of responsivity, they had varying degrees of interpretability and feasibility. No single scale was found to be optimal for use with all types of pain or across the developmental age span. Specific recommendations regarding the most psychometrically sound and feasible measures based on age/developmental level and type of pain are discussed. Future research is needed to strengthen the measurement of pain in clinical trials with children.