Peak expiratory flow rate (PEFR) was measured in a cross-sectional study in 861 healthy Danish schoolchildren aged 6-17 years using a Mini Wright peak flowmeter. We found a strong correlation between PEFR and height, age and sex. The results were comparable with those from previous studies using a Wright peak flowmeter. The equation for prediction of PEFR in boys was calculated as (3.8 x height) + (10.6 x age) - 313.2 (p < 0.0001, r = 0.8), and for girls, PEFR = (2.2 x height) + (14.2 x age) - 143.9 (p < 0.0001, r = 0.64). Our results appear to be reliable, as evidenced by the high correlation coefficient in this large sample. Among healthy children without previous asthma, earlier episodes of recurrent wheezing were reported in 8.8% and a significantly lower PEFR was found in this group.