The Convention on Settlement of Investment Disputes between States and Nationals of Other States (ICSID) provides for the settlement of disputes between host States and foreign investors through arbitration or conciliation. The Convention and the Arbitration Rules provides for the possibility of requesting interim measures for the protection of parties` rights and conserving evidence, among others. Although rule 39 of the Arbitration Rules lists some requirements, this article will exarmine those that must be met in the request. We will also deal with the recent amendment of rule 41 (5), that looks for the protection of procedural good faith, guarantees the efficiency of the arbitral proceedings and avoids the multiplication in unnecessary cases, expenses and delays in the final award.