A prospective study following double-contrast knee arthrography was undertaken to compare pain and discomfort experienced at the conclusion of the procedure and for 7 days afterwards. The patients were divided into two groups. Half had the air aspirated at the end of the examination and the other half did not. Twice as many patients in the aspirated group were totally asymptomatic (48% compared with 22%); however, by 7 days after the procedure the numbers of asymptomatic patients were similar in the two groups (64% and 63%, respectively). Thus our conclusion is that air aspiration after double-contrast knee arthrography does reduce short-term morbidity.