This chapter focuses on piecewise‐deterministic models for fatigue crack propagation (FCP) with a particular focus on estimation issues. In this setting, the process is usually observed on a temporal discrete grid and through an additive noise, which makes unknown both the continuous trajectory and the mode. Experimental data obtained by Virkler is a well‐known source of information about the fatigue of engineering materials. The chapter describes the process of the acquisition of these data. It considers stochastic models to describe the evolution of crack propagation in fatigue. Stochastic models for propagation and rupture can be broken down into two families. The first is statistical modeling of crack propagation data, while the second includes that include randomisation stochastic models derived from phenomenological laws. The chapter discusses the use of piecewise‐deterministic Markov processes (PDMPs) for modeling crack propagation, and presents some models found in the literature.