  In this paper, we characterize the stability region for trinomials of the
form $f(\zeta):=a\zeta ^n + b\zeta ^m +c$, $\zeta\in \mathbb{C}$, where $a$,
$b$ and $c$ are non-zero complex numbers and $n,m\in \mathbb{N}$ with $n>m$.
More precisely, we provide necessary and sufficient conditions on the
coefficients $a$, $b$ and $c$ in order that all the roots of the trinomial $f$
belongs to the open unit disc in the complex plane. The proof is based on
Bohl's Theorem introduced in 1908.
