Pulmonary function tests are essential in the diagnosis of asthma but these are seldom performed in preschool
children. Although pulmonary function tests are critical to the diagnosis and follow up of asthmatics, there are
challenges faced when dealing with the child under the age of six years and this leads to the under-utilisation of
these tests. There is now a better understanding of the respiratory physiology in children and newer spirometry
equipment is available with updated reference values for the paediatric age group. In this article the current literature,
with regards to spirometry in the pre-schooler, is reviewed and its value in the young asthmatic child is stated.