Fuzzy inference systems (FIS) are among main applications of fuzzy logic. At the same time, these models do not account for information reliability. The notion of Z-number is used to express fuzzy information and probabilistic uncertainty. In other words, it describes imprecision of information reliability. In this work we consider using Z-number-based relation concept for describing of if-then rules. The related compositional rule of inference is developed. A numerical example for illustration of the proposed concepts is provided for single-input-single output If-Then rule with components described by Z-numbers.