1,4-Naphthoquinone and its derivatives (lapachol, lawsone, bilawsone, vitamin K) were used as antiageing additives in the natural rubber vulcanized at 160 degrees C with S(8) in presence of ZnO. The rubber vulcanizates were aged under action of heat (343 K for 7 days) or UV irradn. (0.7 W/m(2) at 60 degrees C for 8 h) and studied for mech. properties (tensile strength, elongation at break, stress at elongation 100 and 300%). The addn. of the stabilizers (1.2%) resulted in an increase in the ageing coeffs. in all cases. The best results were achieved when lapachol, bilawsone and lawsone were added.