This paper focuses on the problem of robust stability with delay deviation for a linear system including a gamma‐distributed delay with a gap. First, we present the stability analysis of such dynamical systems in the space defined by the (mean‐delay, gap)‐parameters. Next, we present an analytical method to compute the maximum radius of delay deviation without changing the number of unstable roots of the corresponding characteristic equation. The stability crossing curves, derived in some of our previous works, will play a major role in deriving such robustness measure. Illustrative examples complete the presentation.