Antisense RNA technology is a powerful tool to study the metabolic role of enzymes and to produce commercially desirable traits in food crops. This is demonstrated here for the study of pectin degradation during tomato (Lycopersicon esculentumMill) fruit ripening. Two enzymes—polygalacturonase (PG) and pectinesterase (PE), have been down regulated using this technique. Reduced PG prevented pectin depolymerisation during ripening and resulted in fruit with improved storage and transport characteristics. The reduction in PE activity resulted in increased pectin esterification throughout ripening but had no apparent effect on fruit physiology. All other aspects of pectin metabolism tested were unaffected in these transgenic fruit.