In order to investigate the prevalence of pigeon adenovirus (PA) of pigeons in Taiwan, indirect fluorescent antibody test was performed to test the sera from different pigeon lofts in 1994 and 1995. Sixty-three percent of the tested flocks had antibodies to PA and 20.6% of the pigeons in the infected lofts had antibodies to PA. The PA prevalence was correlated to regions (P<0.01) but not to Newcastle disease (ND) prevalence, seasons, and the ages or sexes of pigeons. However, the ND antibodies in unvaccinated flocks were higher than those in ND vaccinated flocks. These results indicated that the pigeon flocks were severely contaminated by PA and ND viruses in Taiwan.