Recently Vicente et al [19] reported about the incidence of hMPV in 89 COPD patients. Five patients (5.5%) were hMPV positive. Two of these patients had to be transferred to hospital. Although this was not a controlled study and not all details of the study are available due to the fact that the data were published in form of a letter, these results support our findings. The incidence of hMPV in this and in our study is low compared to other respiratory viruses. In a similar previous study we found that Picornaviruses were detectable in 36% of AE-COPD patients, Influenza A in 25% and Respiratory syncytial virus in 22%[2]. There is another prospective cohort study of adults in which hMPV was detected in 4.5% of all illnesses. HMPV was most prevalent in young adults with children and in frail elderly from long term care facilities [17] . Unfortunately this report does not specify how many of the elderly patients suffered from COPD. In our asymptomatic smokers without COPD hMPV could not be detected. A recent study investigating nasal secretions from adults with and without respiratory illnesses found hMPV in 5 of 146 ill patient and in none of 158 control subjects, strongly supporting our data [24] . A further recent study found hMPV in two out of 111 adult patients (1.8%) who presented to the emergency department for AE-COPD during 2 winter/ spring seasons in Quebec, Canada, also in support of our findings [25] . In a US American study investigating clinical samples collected between 1991 and 1995, hMPV could not be detected at all in 196 patients indicating important geographical and seasonal differences in hMPV prevalence [26] . Taken together the results presented here are in keeping with other studies in adults and add important information on the prevalence of hMPV in hospitalized AE-COPD.