Spirometry is a widely used lung-function test in school-aged children and adults. It can also be used to test lung function in the pre-school population, provided that they are tested in a child-friendly setting, by experienced paediatric-orientated personnel and in a way that is congruent with their development. Accurate results can be obtained provided care and attention are paid to applying quality-control criteria suitable for this age group. The biggest challenge is to make the testing fun.