This thesis advises on the optimal index construction technique on behalf of the commercial real estate broker organisation Dynamis in the Netherlands. The database contains 1993 rent-renewals in fifteen years of brokerage from 1984 to 1998. Out of the plethora of indices available in the real estate and other literature five basic forms are defined and applied to the database. These are the simple mean and median indices, the weighted average median index, the hedonic indices and a repeat-rent index. This is meant as an onset to further investigation on basis of these basic methods.