This paper investigates the short- run and long-run effects of government size and exports on the economic growth of Iran as a developing oil export based economy for the period of 1974 - 2008 using an autoregressive distributed lags (ARDL) framework. A modified form of Feder (1982) and subsequently Ram’s (1986) model has been applied to include both government size and exports in growth equation. The findings show that in long run and short run the Armey curve (1995) is valid, indicating that both a very big size and a too small size of government are harmful for growth and government should adjust its size. The results also show that total exports, the amount of oil exports in terms of barrels and oil prices affect economic growth positively and significantly both in short-run and long-run. However, non-oil exports do not have a significant effect on growth in the long run