This prospective study examined the influence of aspirating middle ear effusions, immediately prior to ventilation tube insertion, upon the subsequent development of otorrhoea and tympanosclerosis. 50 children were studied and aspiration of effusions did not influence the incidence of purulent otorrhoea or ventilation tube obstruction within 1 month of surgery. The development of tympanosclerosis did not correlate with effusion aspiration, but in those ears which had an effusion aspirated there was a relation between operative bleeding and the development of tympanosclerosis.