Sera from 22 (13 wild and nine captive) European brown bears (Ursus arctos) from Croatia were tested to 18 viral and rickettsial agents. Serologic evidence of exposure was found to the following agents (number positive/number examined): Bhanja virus (3/15), Tahyna virus (3/15), West Nile virus (4/15), Naples sandfly fever virus (1/15), human adenovirus (1/22), influenza A (1/22) and B (1/22) virus, cytomegalovirus (1/22), parainfluenza virus 1 (2/22), Chlamydia psittaci (1/22), Coxiella burnetii (2/22), and canine parvovirus 2 (CPV-2) (7/22). Evidence of exposure to arboviruses was found exclusively among free-living bears. Evidence of exposure to agents usually transmitted directly was predominant among captive bears. Canine parvovirus 2 antibodies were the most frequently found antibodies and the only antibody common to both groups of bears. This may be the first report of antibodies to CPV-2 in bears.