Abstract: Objective: To investigate the relationships between the disease exacerbations and circadian rhythms in patients with chronic obstructive pulmonary disease(COPD).Methods: One hundred and fifty-four patients with COPD were followed up for 3 years.The general condition and exacerbations situation in all patients were recorded.The relationships between smoking,age,sexuality,circadian rhythms and disease exacerbations were analyzed.Results: The acute exacerbation times in 154 cases were 1 401 times,which included the 512 times of awakening type(36.5%) and 889 times of sleep type(63.5%).One hundred and fifty-four cases included the acute exacerbation sleep type COPD in 82 cases(53.2%),acute exacerbation awakening type COPD in 32 cases(20.8%) and acute exacerbation diffuse type COPD in 40 cases(26.0%).The exacerbations COPD in night was most likely to occur in patients with more than or equal to 70 years,smoking male with less than or equal to 70 years and non-smoking female(P<0.05 to P<0.01).Conclusions: The exacerbations of COPD exists the circadian rhythms,the occurrence of which is prone to at night,in sleep type patients,and especially for smoking old male.