Intermetallic γ-TiAl based alloys are in focus of interest because of their excellent mechanical properties at high temperatures in combination with their low density. Currently, they are used as turbine blades in aero engines at service temperatures up to around 1023 K. Therefore, the detailed knowledge of the creep behavior is of major interest. In this study, the influence of differently spaced fully lamellar microstructures on the creep behavior of an advanced micro-alloyed γ-TiAl based alloy, a so-called TNM+ alloy, is investigated. Creep tests at 1073 K using stresses of 150 and 200 MPa are conducted applying a constant load. In order to describe the creep behavior, a so-called one-parameter model, which uses the mean lamellar interface spacing as governing parameter, is adopted. The different lamellar spacings of the specimens are analyzed by means of transmission electron microscopy. Finally, based on a new constitutive law creep curves are calculated and compared with experimentally determined creep curves. The results are discussed in the light of existing literature.