The amatoxin and phallotoxin content of some American specimens of green A. phalloides and white A. bisporigera, A. verna and A. virosa was determined. The analytical procedure consisted of extracting the toxins from dried mushroom tissue, defatting, fractionating the toxins by adsorption chromatography on Sephadex LH-20, desalting and running thin-layer chromatograms of appropriate fractions along with authentic toxin samples. One amatoxin, amanin, was identified by hydrolysis to its component amino acids. Except for some difference in relative amounts of toxins, American and European varieties of A. phalloides were quite similar. Neither phallotoxins nor amatoxins were present in three out of four collections of A. verna; the fourth contained only a trace of β-amanitin. Amanin was the sole amatoxin present in two out of four collections of A. virosa; α-amanitin was the chief amatoxin in the other two. None of the white Amanita species contained phallacidin. The taxonomy of the above species is discussed. A literature report that edible A. rubescens contains phallotoxins was not confirmed.