The presence of several alkaloids in root and aerial parts of Chelidonium japonicum Thunb. has been reported by Slavik [1] on the basis of TLC and PC evidence. We now report isolation and identification of the alkaloids and sterols of this plant. The basic CHCl₃ soluble fraction gave norsanguinarine (1), norchelerythrine (2), bocconoline (3), and a new natural product 6-hydroxymethyldihydrosanguinarine (4). Compounds 5–7 were identified as sanguinarine, chelerythrine and protopine. Compound 8 from the quaternary base fraction was confirmed as choline-HCl. Elution with CHCl₃ afforded compound 9, which included α-spinasterol and its dihydro derivative. KNO₃ was obtained in the separation procedure. The identification of all these alkaloids, except protopine and sanguinarine, are the first reports from this species.