With special emphasis on the paediatric aspects, the importance of pea
k expiratory flow rate measurements in asthma patients is reviewed. Po
rtable peak flow meters allow for regular home monitoring of lung func
tion. Repeated peak expiratory flow recordings by patients at home are
of great value in the diagnosis and the therapeutic management of bro
nchial asthma. Monitoring of peak expiratory flow rates may improve th
e perception of compromised airway function and thereby enhance compli
ance in asthma patients. As a relatively simple form of pulmonary func
tion testing, the measurement of peak expiratory flow rates, however,
cannot substitute for pulmonary function testing by spirometry, flow-v
olume-curves or bodyplethysmography.