The lesser kestrel (Falco naumanni) is a small falcon with a Euro-Central and Asian-Mediterranean range wintering in sub-Saharan Africa. In the second half of the 20th century, the European population experienced a steep decline and was classified as at risk; thus, its biological and ecological aspects have been widely investigated. Nonetheless, data on hematology and plasma chemistry are not yet available. Therefore, hematology and biochemistry parameters were investigated in a sampling population of clinically healthy lesser kestrels (21 female and 10 male adults) from an Italian rescue center during breeding season, estimating the 95% (2.5 – 97.5th percentile) reference intervals (RI) for standard tests based on either parametric or robust statistical methods. The effect of sex on the referenced parameters was also tested and showed no statically significant differences. The established 95% RI highlighted values comparable with those of other similar raptors such as American kestrel (Falco sparverius) and peregrine falcon (Falco peregrinus). As the first recorded hematology and serum chemistry RI, these clinical data could support conservation efforts and clarify the effects of various environmental and ecological factors on the clinical and health status of lesser kestrels, although they should be reinforced with further data from healthy wild animals.