This note presents a simplified approach to Bode’s theorem for both continuous-time and discrete-time systems, along with some generalization. For continuous-time systems, the constraints of open-loop stability and roll-off at s= ∞are removed. A counterexample shows that, when the excess poles / zeros vanishes, the Bode integral drops from infinite to finite value when the open-loop gain crosses a critical value. A revised result is also developed in this note. The salient feature of this approach is that at no stage do we invoke either Cauchy’s theorem or the Poisson integral; the simplified proof relies only on elementary analysis. This approach carries over to the discrete-time case in a straightforward manner.