We study the impact of fairness on the e±ciency of allo- cations. We consider three di®erent notions of fairness, namely propor- tionality, envy-freeness, and equitability for allocations of divisible and indivisible goods and chores. We present a series of results on the price of fairness under the three di®erent notions that quantify the e±ciency loss in fair allocations compared to optimal ones. Most of our bounds are ei- ther exact or tight within constant factors. Our study is of an optimistic nature and aims to identify the potential of fairness in allocations.