Short time-to-market and low costs of projects require effective and efficient management of projects. As progress in projects is not always as what is foreseen and because new projects need to be started up all of a sudden during the year due to fast changing results managing multiple projects simultaneously is essential. Management of projects in multi-project environments is difficult and often faces lots of problems in organizations such as software, research and development, construction and engineering. This article especially fits in with research and development organizations where multiple projects are run concurrently, and resources are important and scarce. In this research, interactive planning methodology is suggested to overcome the problems in multi-project research and development environment.