The one-dimensional Stark-effect Hamiltonian \[ H=-(d^ 2/dx^ 2)+Fx+V(x),\quad F>0\quad on\quad L^ 2({\mathbb{R}}) \] is considered. \(V(x)=W'(x)\), where W(z) is analytic and bounded in \(| Im z| <a\). With H the analytic family of operators \[ H(u)=-(d^ 2/dx^ 2)+Fx+V(x- u)-Fu \] may be associated. The discrete eigenvalues of H(u) are called resonances. Results on resonances (explicit lower bounds of the width \(2^{-1}| Im z_ 0|\) of a resonance, asymptotic behaviour of the resonance when F tends to infinity, connections with the Fredholm determinant) are discovered.