A number of N-glycidyl compounds derived from oxo-substituted nitrogen heterocycles such as diazines, triazines, diazoles, triazoles as well as condensed ring systems containing these units have been synthesised. All products were tested for their antitumor activity against leukaemia in the mouse. Almost all of the approx. 50 di-and triglycidyl compounds showed activity, whereby 5 of them exhibited an increase of lifespan of 200% and more. ...