The human coronaviruses (HCoV) OC43 and 229E are common causes of upper respiratory tract infections. Severe diseases were rare, however, until the emergence of the severe acute respiratory syndrome (SARS)-CoV in 2003. Since then, other novel CoV (NL63 and HKU1) have been described, and they have caused respiratory infections worldwide. Potentially exposed laboratory workers or animal handlers with rapidly progressive pneumonia not responding to standard antibacterial coverage must be isolated with contact and droplet, and for specific situations, airborne precautions, till rapid tests of respiratory and faecal samples are negative for SARS-CoV. Generally, the viral loads collected at different anatomical sites correlate with the severity of symptoms and mortality. Shedding of SARS-CoV peaks at day 10 after the onset of symptoms, which theoretically allows ample time for antiviral treatment. The disease is characterized by uncontrolled replication of the virus and a prominent pro-inflammatory response. No randomized controlled trials with a specific anti-coronavirus agent have been conducted with respect to therapy or prophylaxis. Reports using historical matched controls have suggested that treatment with interferon alfacon-1 (a synthetic interferon) combined with steroid, protease inhibitors together with ribavirin, or convalescent plasma containing neutralizing antibody, could be useful. Prophylaxis with interferon or hyperimmune globulin may be considered for unprotected exposure. The role of immunomodulators to decrease excessive inflammation remains elusive. Other non-SARS-CoV infections are generally milder in immunocompetent hosts, and scientific data on antiviral treatment of these viruses are scarce.