The influence of hunting-season stage (deer hunted at the start versus deer hunted at the end of the season) and ripening conditions (natural versus controlled drying rooms) on nitrogen fractions and degradation of myofibrillar proteins were studied in chorizo sausages made with venison. Variations of nitrogen fractions during 21 days of ripening were found. In all batches, myofibrillar protein content decreased and proteolysis indices were between 4.6% and 14.4% at the end of ripening. However, after 45 days of storage in vacuum packs no significant variations in nitrogen fractions contents occurred. Similar changes of electrophoretic profiles of myofibrillar proteins in batches processed under controlled conditions took place during ripening, however samples of batches processed in natural drying rooms did not show the same variation. Ripening conditions influenced the relative density of bands corresponding to 45 (actin), 37 (T-troponin), 35 (tropomyosin), 20 (C-troponin) and 19kDa, after 21 days of ripening. Hunting season stage influenced the relative density of the 49kDa band after 21 days of ripening. Changes on proteins profiles were found after storage in all four batches.