New epidemics often provide a unique opportunity to gather and study evidence of a micro-organism’s etiological link with disease. This holds good when studying a serious ailment such as bronchitis-pneumonia. Between 1990 and 1991 there was an outbreak of C. pneumoniae infections among Univ. of Washington students. Following a study, evidence of an etiological link between bronchitis-pneumonia with C. pneumoniae infections was found.