Objective: To introduce the method of avuncular index (AI) calculation.
Methods: Identity by decent coefficient, coancestry coefficient and AI law were employed in identification of uncle-niece relationship, when autosomal STR loci were detected to determine controversial uncle-niece relationship.
Results: The results of AI calculation were coincidental using identity by descent coefficien, coancestry coefficient and AI law.
Conclusion: The results are coincidental using three methods in the different situations. AI index is higher with participation of children's mother.