Overall thirty-nine patients were studied, their clinical and immunological indices suggesting atopic form of bronchial asthma (BA), as were eighty children presenting with recurrent episodes of obstructive bronchitis. With PC2OH test being used to identify unspecific hyperreactivity of bronchi in BA patients actual positive results are recordable more often than they are with calculation of the parameter characterizing lability of bronchi, while false positives are less common. There were also more false positives with PC2OH test than they were the method of comparison.