Brown pelicans (Pelecanus occidentalis) are becoming increasingly common visitors to rehabilitation facilities due to entanglement in fishing lines and hooks. As such, it is important to establish baseline medical data, including diseases with zoonotic potential, for accurate health assessment of this species. The purpose of this study was to survey brown pelicans in south Florida for prevalence of antibodies to common avian diseases. Blood and feces were sampled between October 1998 and January 1999 from 31 healthy but permanently flightless pelicans and 48 wild caught healthy pelicans from a rehabilitation facility on the east coast of Florida. Serologic tests of healthy birds indicated 79% of pelicans were seropositive for Chlamydia antibodies. Enzyme-linked immunosorbent assays (ELISA) on a subset of these birds were positive for Chlamydia antigen in 89% of birds. However, Chlamydia DNA probe tests were all negative. Pelicans were also seropositive for Aspergillus antibody (75%) and Sarcocystis antibody (54%). Seroconversion was rare for Mycobacterium (11%) and non-existent for Newcastle’s disease virus. Overall, the level of seroconversion was great, however, antigen detection and/or shedding was low. As these pelicans routinely come in contact with veterinarians, zookeepers, and rehabilitators, the potential for disease transmission places immunocompromised individuals at increased risk. In light of the zoonotic potential of chlamydiosis and aspergillosis, more studies are needed to elucidate conditions for active shedding and for health assessments of other seabird species as potential carriers of these and other zoonotic diseases.