Between August and December 1996, there was an outbreak of a debilitating skin disease attributed to Sarcoptes scabiei infection in mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park in Uganda. All four members of a gorilla group which had been habituated to tourists were clinically affected; the infant male gorilla was most severely affected and died, the juvenile male showed serious manifestations of the disease and the two adult animals showed milder signs. The three older animals recovered after a single intramuscular dose of ivermectin. S scabiei mites were observed on skin scrapings and biopsies taken while the juvenile was immobilised and in postmortem samples taken from the infant. The clinical signs did not recur during the following year, and no other gorilla groups in the park were observed to be clinically affected.