A series of new compounds has been prepared by reacting aliphatic and aromatic aldehydes with ethylene dithiosemicarbazide. The nature of these new dithiosemicarbazones has been deduced from their infrared spectra, from the products of the ferric chloride induced oxidation of two of them, and from the formation of 1:1 copper complexes of several of them. Since the copper complexes are paramagnetic, the copper must be present in the cupric oxidation state. A structure has therefore been proposed for the complexes which involves bonding between copper and both thiocarbonyl groups in the dithiosemicarbazone molecule.Several of the compounds prepared in this work exhibit an antifungal action against the cellulolytic microorganism Chaetomium globosum.