In August 2003, the Alaska SeaLife Center implemented a new research program focusing on free-ranging juvenile Steller sea lions (Eumetopias jubatus) from the endangered western stock. This project provides the ability to study wild animals for up to three months in a specialized quarantine facility, after which time the animals are returned to the wild. A major objective of this program is a comprehensive health and disease monitoring protocol which was developed to evaluate health and disease at admission and release, as well as for comparison to free-ranging control juvenile Steller sea lions (SSL) captured from the same geographical location. Serum was collected at capture from 23 transient juvenile SSL (age 1-2 years) along with 14 free-ranging juvenile SSL and has been tested for exposure to typical marine mammal infectious diseases. Serum was also tested at release from the transient juvenile SSL. All samples tested to date have shown no evidence of exposure to Brucella spp., morbillivirus or Toxoplasma gondii and animals in temporary captivity showed no increase in exposure to Leptospira spp. or phocine herpesvirus-1. Tracheal mucous and feces were collected opportunistically to evaluate parasite load. Nasal, rectal, preputial and vaginal swabs were screened for both normal and potentially pathogenic bacteria. Additional sensitivity testing was performed on E. coli isolates cultured from rectal swabs to assess whether antibiotic resistance had developed over the course of temporary captivity. These isolates have shown no resistance upon admission or release to 12 commonly used antibiotics. In summary, these results show that Steller sea lions held in temporary captivity for up to three months remained healthy and did not show evidence of exposure to disease or develop antibiotic resistance that could place free-ranging animals at risk for disease following their release.