The contents of the steroidal alkaloid solasodine and of solasodine-like alkaloids in samples of 85 native Australian Solanum species have been determined. Leaf, stem and fruit of 74, leaf and stem of seven, and leaf only of four species were examined. Samples were extracted with ethanol, the resulting glycoalkaloids were hydrolysed and the amount of alkaloidal aglycone was estimated by a colorimetric procedure based on solasodine as the standard. The solasodine present in the extracts was identified by comparison with an authentic sample by means of thin-layer chromatography. Twenty-nine Australian species were shown to contain appreciable amounts of solasodine. Of all the species examined, S. aviculare, S. laciniatum and S, simile were found to have the highest content of solasodine. Tomatidine has been isolated from S, dimovphospinum. S, callium contains appreciable quantities of the two new alkaloids 25-isosolafloridine and solacallinidine. S, dunalianum, which has probably been introduced into Australia from New Guinea, contains the new alkaloid soladunalinidine and small amounts of tomatidine. © 1978 CSIRO. All rights reserved.