Spontaneous cough is a symptom with diffuse diagnostic significance for childhood asthma. Information on the interrelations between presence/frequency of cough and other symptoms of asthma are not available to the physician. Tracheal sounds were continuously recorded in the homes of 60 children with and 30 without asthma, at 72 and 24 h, respectively. Presence and frequency of cough and presence of wheeze were scored by trained examiners. Wheeze was used to indicate airway obstruction during hours when peak expiratory flow (PEF) values were not available. PEF and self-reported dyspnea were assessed every 4 h. Results showed that asthmatics coughed significantly more often than control subjects during exacerbations, but not during remission. The highest diagnostic sensitivity percentages of cough were 72% for wheeze and 69% for a reduction in PEF > 20%. However, the diagnostic specificity was poor, 41% for wheeze and 34% for a reduction in PEF > 20%. Cough and dyspnea were independent. Three children did not cough during exacerbations. Persistent, isolated cough was observed in two children. It was concluded that spontaneous cough is modestly predictive of asthmatic exacerbations, but not of a diagnosis of asthma or severity of asthma.