Summary Continuing preceding work (1,2), a series of tests has been carried out on the toxicological evaluation of samples of different fatty esters obtained from several manufacturers. Eye irritation tests and skin irritation and sensitisation tests were carried on the rabbit following the official French methods with minor modifications. When tested pure, nearly all the isopropyl and butyl esters used gave some adverse reactions. Only one sample (out of two tested) of isopropyl stearate appeared to be well tolerated although the primary irritation index on skin was greater than one. The two esters with the greatest adverse skin reactions were isopropyl isostearate and one of two isopropyl linoleates. Ten per cent aqueous dispersion showed considerable diminution of the adverse reactions in the majority of the cases. Considering the results obtained in this paper together with those published previously (1) being twenty-seven samples covering fifteen different fatty esters, the worse reactions were obtained with the C(8), C(12), C(14) saturated together with the oleate and linoleate esters. Isopropyl palmitate, stearyl heptonate and arachidyl propionate were the best tolerated as pure materials. Other adverse reactions were obtained with the isopropyl, butyl and octyl stearates and isostearates (except for one of two isopropyl stearates) and from these results appears that the alcohol moiety plays little part in irritation when compared with the fatty acid chain. Examination of peroxy values indicates that these have a significant adverse effect for oleates and linoleates.