We conducted a questionnaire survey on the onset time and frequency of asthmatic symptoms in adults with bronchial asthma who were regular clinic attendees in 17 sites in Chiba Prefecture, and analyzed 513 respondents. As a result, the frequency of wheezing was 54.6%, the highest of all symptoms. Feeling of chest discomfort was 32.2%, followed by asthma attack (13.8%), cough (8.7%) and dynpnea (6.8%). Asthmatic symptoms were highest from midnight to early morning, with the peak at around 4 o'clock am. The same pattern was seen regardless of the severity and types of asthma. This survey also showed that conventional anti-asthmatic therapies decreased the frequency of nightly asthmatic symptoms from the baseline: 7 times or more per week reduced from 44.9% to 16.1%, 3 times or more per week from 76.8% to 40.4%, and at least once per week from 94.4% to 71.5%. The results suggest that it is important to take another therapeutic strategy, which can administer medications at the appropriate time according to the circadian rhythms in asthmatic patients to better control asthma.