The invention relates to heterocyclic ester compounds which have been found to be effective ultraviolet stabilizers. The invention also relates to ultraviolet degradable organic compositions containing an amount of a heterocyclic ester composition to prevent such degradation. These stabilizers are effective in the presence of other additives commonly employed in polymeric compositions including, for example, pigments, colorants, fillers, reinforcing agents and the like. These ultravoilet stabilizers may be incorporated into the organic compositions such as polymers by adding to the polymer melt or dissolved in the polymer dope, coated on the exterior of the shaped or molded article, film or extruded fiber.