Carotenoid-based coloration of plumage and bare parts is widespread among avian taxa (McGraw 2006) but in most species carotenoid coloration is found mainly in adults. Juvenile carotenoid ornamentation is believed to be much less common and is usually expressed in a reduced form (Kilner 2006). Extensive studies of factors governing juvenile plumage coloration have been conducted in Great Tits Parus major and Blue Tits Cyanistes caeruleus (e.g. Biard et al. 2006). Analogous surveys of bare parts of nestling integuments, especially in nonpasserines, are very rare (but see Casagrande et al. 2008). Adult White Storks Ciconia ciconia of both sexes exhibit bright red coloration of their bills, legs, and on the bare skin of their chins and throats (Cramp 1998). Recent studies have revealed that these integuments are coloured by astaxanthin, which is a carotenoid pigment (Negro & Garrido-Fernandez 2000, Negro et al. 2000). The legs of newly hatched nestlings are pink and with age turn grey-black (Cramp 1998). Typically, the dull red coloration of the legs of juveniles appears only after they fledge (Cramp 1998). In some Spanish populations of White Storks that have carotenoid-rich diets, nestlings have beaks and legs that are nearly as red as those of adults (Negro et al. 2000). Such rapid development of coloration in nestling White Storks seems to be an exception. However, in some populations, nestlings exhibit grey-black leg coloration accompanied by pale yellow to pale orange patches (J. Kosicki unpubl. data). These observations suggest that some carotenoid pigments may exist in legs of juvenile nestlings of populations other than the Spanish population (Negro et al. 2000). Here, we measure the integument coloration of White Stork nestlings. Based on the spectral properties of the reflectance data we predict which pigments are responsible for the coloration. We also assess how coloration of the leg integument correlates with nestling age and growth rates. This study represents the first use of objective measures of spectrophotometry to describe integument coloration of White Storks and probably the first objective measure of coloration of any stork.