Abstrucf. The works related to the disequilibrium theory often show that situations of classical unemployment and of Keynesian unemployment coexist on a long-term basis. The following study deals with a theoretical model of mixed unemployment reflecting this coexistence. In this model, prices are assumed to be flexible upward, but not downward.Hence, classical unemployment leads to inflation, without quantitative rationing on demand, which is closer to reality.The study analyses the asymmetric relations between the classical and the Keynesian sectors as well as the resulting implications for economic policy. What comes out is that differentiated policies always have a stronger impact than aggregate policies. The highest level of efficiency is obtained by stimulating the supply of firms set in the classical situation, provided that one acts on the non-wage determinants of supply in order not to further depress the outlets for firms set in the Keynesian situation.