Bilateral myringotomy with insertion of ventilation tube (grommet) is the most common surgical procedure done on children under general anaesthetic. A prospective study was conducted on children undergoing grommet insertion to ascertain any relationship between exposures of passive smoking to the outcome of grommet insertion. Six hundred and six children (with 1174 ears) who underwent grommet insertion for recurrent secretory otitis media were followed up till the grommets were extruded. Thirty-three children (65 per cent), whose mothers smoked when they were pregnant, had bilateral narrow external ear canals. The median survival rate of grommet was 59 weeks in children who were exposed to passive smoking as compared to 86 weeks for non-exposed children and the extrusion rate of grommet was 36 per cent higher at the end of one year if both parents smoked compared to the non-smoking group. Post-extrusion myringosclerosis was 64 per cent if both parents smoked and less than 20 per cent if neither parents smoked. It is concluded that post-operative infection rate, attic retraction, post-extrusion myringosclerosis and permanent perforations of tympanic membrane were more common in children exposed to passive smoking. The study provides further support to professional and governmental advice that passive smoking is harmful.