Nestling sexing by biometric and molecular analysis in two diurnal raptors. The following data were collected during a long term study in France of the Common Buzzard Buteo buteo and the Short-toed Eagle Circaetus gallicus. Even though females of these two species are significantly larger than males, biometric parameters show substantial overlaps between sexes, so that in-hand sexing from morphometrics alone can be hazardous. Therefore, we have been looking for a reliable method of sexing nestlings, based on discriminant analysis of measurements, computed between groups of DNA determined males and females. In this paper, we give simple (linear) functions of a few parameters, allowing the prediction of the sex of a good proportion of the juveniles: Roughly 85% of Short-toed Eagle nestlings, older than 40 days (wing-length > 170mm), and 90% of Common Buzzard nestlings, from the age of 4 weeks (wing-length > 205mm), can be sexed correctly.