There is a need for simple asthma outcome measures for primary care which are not only valid in terms of their relationship with lung function but also in terms of pragmatic psychological constructs. This study assesses the usefulness of adding items on the degree of 'bother' and 'fright' caused by the condition to a previously validated simple asthma morbidity index. A postal questionnaire survey comprising a simple asthma morbidity index and questions on 'fright' and 'bother' was conducted in one general practice in the north-east of England. Responses were obtained from 570 individuals. Of these, 184 (32%) reported low, 133 (23%) medium and 253 (44%) high morbidity. Twenty-nine per cent of respondents had felt frightened by their asthma in the previous 4 weeks. Both the 'fright' and 'bother' items were significantly associated with the morbidity index. The addition of 'bother' and/or 'fright' questions may improve both the content, construct and predictive validity of the morbidity index, but this needs to be established prospectively.