“…Unbound fatty acid concentrations of the order of micromolar (/an) inhibit lipolysis by adipose tissue (Rodbell, 1965), are potent uncouplers of oxidative phosphorylation and may inhibit mitochondrial respiration with certain substrates (Wojtczak, Bogucka, Sarzala & Zaluska, 1969). In this context it is interesting to note that unbound fatty acids are likely candidates for the 'toxic factor' found in the serum of animals infected with malaria and reported to cause inhibition of oxidative phosphorylation and also cell damage (Riley & Deegan, 1960;Riley & Maegraith, 1961;Maegraith, 1966). Directly lytic material has also been found in infected serum (Laser, 1948;Fife, von Doenhoff & d'Antonio, 1972).…”