One of the most important problems in lemon growing is the physiological disorder known as "peteca", which is characterized by causing cell dehydration and death in the albedo tissue with a subsequent necrosis of the surface zone of the fruit. This damage shows characteristics quite similar to those resulting from chilling injury in citrus fruit, where surface damage of fruit and dehydration of albedo cells also occur. Resistance to chilling injury shown by grapefruit would be related to increased proline content in the albedo (Purbis, 1981). In this study, proline content of lemons cv. "Fino" 49 from two groves, one in Curacaví (33°25.778 S - 71°02.292 W, 196 m above sea level) and the other in Mallarauco (33°94.984 S - 70°58.921 W, 269 m above sea level), was analyzed and determined. The Curacaví grove had a low incidence of peteca, whereas the Mallarauco grove exhibited a high incidence of this disorder. Significant differences in albedo proline content were found between both groves and content of this amino acid was highly associated to the degree of peteca incidence. Proline might be playing a role in the lower incidence of "peteca" in winter lemon fruit.