Eric Rhenman became a well known person in the academic world and within the business community both in Scandinavia and elsewhere. He did write numerous books and articles within the areas of business economics and business management. He was a professor at the Stockholm School of Economics and at the University of Lund as well as a visiting professor at the Harvard Business School.

In 1966, Eric Rhenman, together with four colleagues from the Stockholm School of Economics, established SIAR, a research organisation which through its subsidiary SIAR Planning AB later on became one of the most influential international strategy consulting organisations with offices in Boston, Hamburg, Helsinki, London, Lund, Milan, Paris, Riga, Singapore, St Petersburg, Stockholm, Tallinn, Tokyo, Vilnius and Warsaw.

In 1991 the consulting arm merged with the French firm Bossard and Eric Rhenman became one of the senior executives in the joint SIAR-Bossard organisation. Eric Rhenman passed away 1993. A few years later SIAR-Bossard became a part of the Cap Gemini world-wide organisation. The SIAR foundation continued from 1991 as an independent research organisation and with Eric Rhenman as chairman of the board up to his death.