The incidence of tracheal tube cusf rupture was noted in 30 polyvinyl chloride tracheal tubes lubricated with three dgferent solutions. All cuffs moistened with water were intact after 2 hours of cuff injution whereas two of I0 lubricated with 4% lignomine solution had burst. Both of these had leaked at the site of cuff attachment to the tube. Fifty percent of tubes lubrimted with Astra lignocaine spray burst during the study. Four of the jive had developed pinholes in the c u f i~ themselves. The remaining 50% of this group showed marked distortion and thinning of their intact cuff walls. The implications of these findings are discussed in view of' the widespread use of PVC tracheal tubes.