Between 1976 and 1985 necropsies were conducted on 55 free-living and 18 captive echidnas originating from several localities in Victoria, Australia. Injuries arising from motor vehicle accidents were the most common cause of death (24 of 55; 47%). An additional nine live echidnas were presented for clinical examination for dog or fox wounds (eight), or wire snare wounds (one). Incidental infestations with ticks (Aponomma concolor) on the skin or in the ear canal (eight of 82; 10%), and infections with intestinal cestodes (Linstowia echidnae) (nine of 73; 12%) and intestinal coccidia (three of 73; 4%) were found. Intestinal trichostrongyloidosis (four of 55; 7%), purulent bronchopneumonia (three of 55; 5%) and septicemia (three of 55; 5%) were the major disease syndromes seen in free-living echidnas. Other conditions seen were a non-specific enteritis, toxoplasmosis and bacterial granulomata. The latter lesion and the bronchopneumonia may have arisen from soil bacteria entering the body during digging and feeding activities. The echidna's ability to resist these infections may be lowered due to its low normal body temperature, and periods of torpor. Several young echidnas suffered starvation or gastric dilatation soon after capture, due to the rejection or fermentation of food offered. Captive echidnas suffered from acute salmonellosis (six of 18; 33%), toxoplasmosis (two of 18; 11%) and exposure (two of 18; 11%).