In this paper, we look for the relevance of chaos in the well-known Hicks-Samuelson's oscillator model investigating the endogenous fluctuations of the national income between two limits: full employment income and under-employment income. We compute the Lyapunov exponent, via Monte- Carlo simulations, to detect chaos in the evolution of the income between both limits. In the case of positive Lyapunov exponent and large values of the parameter (i.e. marginal propensity to consume and technical coefficient for capital), the evolution of income (...) is seen to be chaotic. The model also may contain a quasi-periodic attractor that can be chaotic or not. (shrink)