Envenomation by the Sydney funnel-web spider may lead to serious illness or death. After an antivenom which had been raised in rabbits was proven to reverse the signs of envenomation in animals, a trial was conducted in patients. Nine patients (aged 3-82 years) with severe envenomation by funnel-web spiders received treatment with an antivenom to the venom of Atrax robustus. Concomitant diseases in the victims included rheumatoid arthritis, diabetes mellitus, complete heart block, pyrexia of unknown origin, and carcinoma of the ovary, which were being treated with appropriate drugs. Because of the introduction of the antivenom, the syndrome which previously caused either death or a hazardous illness which required two to three weeks of hospital care now became an illness lasting one to three days. So far there have been no definite adverse reactions to the antivenom. There have been no deaths since the antivenom has been used, and it is hoped that human fatalities as a result of funnel-web spider envenomation will become a thing of the past.