Major histocompatibility complex (MHC) are classical examples of good genes because of their crit- ical participation in fighting and eradicating pathogens. Here, we investigated the inheritance of alleles across a highly polymorphic MHC class II B gene in a socially monogamous raptor, the lesser kestrel Falco naumanni. Allele segregation patterns from parents to offspring were monitored in 44 breeding pairs and 228 nestlings. We found that a particular array of closely related alleles, defined by the presence of two of the three commonest alleles (only three alleles exhibit frequencies larger than 10 % in the studied populations), showed significant transmission ratio distortions when inherited from males (k00.702±0.188, p<0.001), but not when inherited from females (k00.563±0.207, p00.19). We believe that this result is consistent with the targeting of genetically loaded spermatozoa by female kestrels. Our anal- yses do not allow discerning, however, whether this pattern is predominantly driven by sperm competition or differential maternal allocation. This trend, nonetheless, would agree with the contrasting relative frequencies of these alleles between western and eastern populations of lesser kestrels and sustains their contemplation as locally adapted alleles, as suggested in previous studies. Ours is one of the very few studies support- ing the MHC-based female cryptic choice in birds and opens inspiring lines of research. In particular, future studies addressing the influence of candidate MHC alleles on indi- vidual fitness and their effect on maternal adjustments associ- ated with reproduction should be encouraged.