The resistivity inhomogeneity in neutron transmutation doped (NTD) silicon is a function of both the initial inhomogeneity before transmutation doping and the final compensation ratio after transmutation doping which, in turn, is a function of the irradiation thermal‐neutron fluence. Calculations of this inhomogeneity &Dgr;&rgr;/? as a function of compensation ratio are presented. These calculations are then compared to experimental data obtained by probe measurements of NTD silicon compensated to resistivities as high as 100 000 &OHgr; cm. Calculations are also presented which yield the maximum possible mean resistivity which can be obtained, given an initial &Dgr;&rgr;/?, before fluctuation‐induced mixed typing occurs.