The ciliary beat frequency measurements taken from a nasal polyp from a cystic fibrosis patient were similar to that of the control nasal polyps. The addition of a ciliotoxic lectin produced by Pseudomonas aeruginosa stopped the beating of the cilia as in the controls. This reaction could be blocked by the pre-incubation of the lectin with its inhibitor fucose. As in the control, the addition of fucose after the cilia had slowed resulted in a return to normal ciliary beating within 24 hours. This shows that the delta F508 CF mutation observed in this patient does not affect ciliary beating and suggests that treatment with fucose in the early stages of a Pseudomonas aeruginosa infection could be advantageous for cystic fibrosis patients.