Using case reports and a review of the literature, the clinical features of envenomation by the genus of Australian funnel web spiders known as Hadronyche, are characterised. Five cases are reported here, including the first life-threatening envenomation by Hadronyche species 14 (the Port Macquarie funnel web). Two severe envenomations by Hadronyche cerberea (the Southern Tree funnel web) and one each by Hadronyche formidabilis (the Northern Tree funnel web) and Hadronyche infensa (the Darling Downs funnel web) are also described. The clinical experience of the authors' provided the five cases described in detail one of which has previously been reported in brief. Eight cases of Hadronyche envenomation from the literature (Medline 1966-1998 and Embase 1980-1998) were analysed in order to draw comparisons between this syndrome and the well described envenomation syndrome of Atrax robustus (the Sydney funnel web). Reports of funnel web spider antivenom use to Commonwealth Serum Laboratories (CSL) between 1995 and June 1998 were also examined. The biology of these dangerous spiders, their geographic distribution, venom characteristics and management issues are addressed. It is concluded that bites from at least six Hadronyche species have produced a life-threatening envenomation syndrome clinically indistinguishable from that of Atrax robustus. Atrax robustus derived antivenom is effective although antivenom requirements may be greater than for Atrax envenomation. Antivenom supplies are limited and sufficient stocks to treat a severe envenomation are unlikely to be found in any one institution. Pressure-immobilisation first aid is effective in delaying onset of envenomation, may enhance local inactivation of venom and early removal can result in rapid clinical deterioration.