This paper treats with two modeling techniques: Nonhomogeneous Continuous-Time Markov Chains (NH-CTMC) and Systems Dynamics (SD). In general, each of these focuses on different types of problems. While the NH-CTMCare used in the modeling of stochastic processes, the SD is focused on modeling a system from functional relationships between its components. However, it is demonstrated that the concepts and tools of the SD can be effectively used in modeling of NH-CTMC by means of the building and simulating an Equivalent Systems Dynamics Model (ESDM) representing the state probabilities over time. The ESDMis based on mathematical equivalence between the two models, which is shown through an example and relevant considerations in its application are summarized. This proposal could be used to study reliability in complex systems using more simple calculations.