This work is presenting some forecasts of key developments aggregate of public pension system under transition of the Romanian economy from the status of "in transition" to the market economy - necessity, implementation and immediate effects. In the same time, is presenting theoretical-methodological bases of the macroeconomic forecasting model, the labour market and population - MITGEM, the impact of EU integration on macro-economic developments of the main variables influencing the profitability of pension funds ; alternative forecast scenarios - as the main way of operating the MITGEM model. Also, is presenting the prospective of the main variables of pension system structure of the model scenarios within MITGEM, average pension, the average retirement pension, disability pension and survivor's pension in Romania.