The noses of patients with clefts are often functionally inadequate. The aim of the present study was to evaluate the correlation between size of the maxillary cleft in infancy and size and function of the nasal airway in adults with unilateral cleft lip and palate (UCLP). This is a long-term follow up study including 53 patients with UCLP born between 1960 and 1987 and treated at the Cleft Lip and Palate Centre, Uppsala University Hospital, Sweden. Lip repair was performed at 3-4 months of age followed by either a one-stage or a two-stage palatal closure. The size of the cleft was measured on infant maxillary dental casts. Nasal minimum cross-sectional area (cm(2)) and volume (cm(3)) (acoustic rhinometry), air flow resistance (Pa s/cm(3)) (rhinomanometry), peak inspiratory flow (l/min) (peak nasal inspiratory flow) and number of identified odours (Scandinavian odor-identification test) were assessed in adulthood. The size of the maxillary cleft varied considerably at infancy. The size of the nasal airway and its function on the cleft side in adulthood were reduced compared with the non-cleft side, but no correlations were found between size of the initial cleft in infancy and size and function of the nasal airway in adulthood. In adults born with UCLP, therefore, size of the maxillary cleft in infancy does not seem to affect size and function of the nasal airway in adulthood.