The variation of post-harvest behavior of peroxidases (POX), polyphenol oxidases (PFO) and carotenoid compounds of tomatoes treated with UV-C was studied in order to extend its useful life and at the same time obtain a beneficial effect on the quality of it. The optimal radiation dose was 4.57 kJ. s-1. m-2 for 16 minutes on samples placed 10 cm from the lamps. Under these experimental conditions the carotene content increased in the treated samples compared to the controls, however, longer exposure times generated harmful effects such as loss of turgor, appearance of spots, degradation of carotenoids and burns in the epidermis. The higher irradiation dose showed the lower development of microorganisms. An effect of the treatment towards the end of the conservation period was observed in relation to the count of molds and yeasts, presenting a lower load of this type of microorganisms with respect to the controls. Significant differences are observed in the enzymatic activity of POX, which would indicate an inductive effect of the treatment on the activity of this enzyme. On the other hand, although the polyphenoloxidase content was slightly higher throughout the study period, there were no significant differences in relation to the controls. This would indicate a complementarity in the antioxidant activity of PFO and greater prominence of the POX in the defense system.