Through lack of effective primary prevention of childhood asthma, good secondary prevention program by early detection of the disease, is needed. Therefore we sought to estimate sensitivity, specificity and predictive values of asthma symptoms questionnaire. In Mikołów District 899 school children, aged 8-9 years were screened using respiratory symptoms questionnaire (80% of all in that age group). Question on "attacks of dyspnea" had the best positive predictive value (28%), high specificity (61%) and sensitivity (92%). Positive predictive values for other single symptoms were lower, but comparable values had "attacks of dyspnea with wheezing" (25%), with lower specificity (35%) and high sensitivity (95%). These findings confirm that standard questionnaire is a useful instrument for the childhood asthma screening. Until design and validation of more advanced screening tools, early identification children with asthma by questionnaire should be basic in prevention programs of the disease.