UNASSIGNED : Enterovirus D68(EV-D68) is an emerging disease that affects mostly children. There have been few relevant investigations to clarify transmission and seroprevalence within daycares and kindergartens. METHODS : This prospective cohort study investigated respiratory viral transmission among preschool children in a public kindergarten in Taipei City of Taiwan between September 2006 and June 2008. After children were enrolled, daily monitoring of illness and regular biweekly physical examinations were performed. We performed viral isolation to detect acute EV-D68 infection and neutralization tests to detect specific EV-D68 antibodies and to measure the seroprevalence and seroconversion rates. RESULTS : Among 190 kindergarten attendees aged between two to five years old, nine children had acute EV-D68 infection in September 2007. The clinical manifestations included pharyngitis, cough and other unspecified upper respiratory tract infection. None of the infected children had acute flaccid paralysis or severe respiratory illness. The phylogenetic tree of partial viral protein 3 and viral protein 1 was clustered in clade A1. The EV-D68 seropositive rate increased from 19% (25/130) at the beginning to 67% (83/124) at the end of the study. The seroconversion rate of 49 children with initial seronegative and paired sera was 73% (36/49). CONCLUSIONS : A high seroconversion rate (73%) for EV-D68 was found among kindergarten attendees, which indicates preschool-aged children are highly susceptible to EV-D68 infection and that the disease burden may be extremely underestimated. Once EV-D 68 circulates, preventive measures may be advocated, especially within kindergartens or daycares, to reduce transmission and subsequent development of severe cases.