The aim of this study is to assess the contribution of the correlation between absorbed fractions of organs/tissues, to the overall relative uncertainty of the ingestion dose coefficients, otherwise of biokinetic and dosimetric models of α-, β-, αγ-, and βγ-emitters. ²³⁸U an αγ-emitter, and ²¹⁰Pb an βγ-emitter were considered for calculations. The overall relative uncertainty of the ingestion dose coefficient ranging from 124% to 175% for ²³⁸U, and 206% to 287% for ²¹⁰Pb was assessed, by ranging the relative uncertainty on the numbers of transformations, the absorbed fractions, the radiation and tissue weighting factors, and the wall parameter from 5% to their nominal values in the literature and by considering the weighting correlated coefficient between absorbed fractions at 5%, to take into account of the importance of the target or source organs/tissues according to their specific absorbed fractions. Finally the correlation between absorbed fractions of organs/tissues mostly affects the weighted relative uncertainty of absorbed fractions at around 88%. But because of the low contribution of this parameter in the assessment of overall relative uncertainty, this correlation between absorbed fractions has a very low impact in the final result.