Citrus fruit are considered one of the main sources of ascorbic acid for human nutrition and health. The concentration of AsA in parts of fruits of different Citrus species has led to the general conclusion that flavedo is the richest tissue compared to albedo or pulp [25,39,40]. Similarly, differences in AsA content between fruit tissues have also been detected in other species, such as apple [31]. The reason for that contrasting difference in AsA levels between external and internal fruit tissues is unknown but it has been postulated that since the peel constitutes the first barrier of the fruit and the interphase with the environment, directly exposed to radiation, wounding, wind, etc., may require a more efficient antioxidant system to cope with biotic and abiotic stresses [41]. Moreover, light exposure has been also shown to stimulate AsA content and the expression of AsA biosynthetic and recycling genes in the peel of apple fruits [31] and vegetative tissues of rice and Arabidopsis [33,42]. Therefore, we have investigated whether differences in AsA concentration between flavedo and pulp of Citrus fruits could be at least partially mediated by the direct exposure to light.