Objective To provide reliability and validity data on a computerised dental anxiety scale (the Smiley Faces Program or SFP) for children using faces as a response set. Setting Five schools across Derby, Newcastle-upon-Tyne and Shropshire. Subjects and method The SFP was completed by 464 children (mean age 10.8 years). For validity purposes, 241 children also completed two other children's dental anxiety measures (the Modified Child Dental Anxiety Scale and the Dental Fear Survey). For test-retest purposes 100 of the children completed the SFP two weeks later. Results The SFP demonstrated good internal consistency (α= 0.8), test-retest reliability was good and significant correlations were found between the SFP and the other measures. The children rated the local anaesthetic and drill as the most anxiety-provoking items. Conclusion This study suggests that the SFP is a valid and reliable measure for assessing children's trait dental anxiety and may help encourage dentists to formally assess dental anxiety.