Effects of plastic deformation on the normal, zero‐field, and mixed‐state specific heat of the type‐II superconductor niobium were experimentally investigated. A high‐resolution ac calorimetry technique was developed and used to study the effects of plastic deformation on the specific‐heat superconducting transition in fields up to 2750 Oe. A method for the analysis of high‐resolution specific‐heat data near the superconducting transition is presented and used to determine &kgr; variations (within a material) caused by plastic deformation. The effects of plastic deformation on the bulk superconducting transition temperature and width are also shown. Measurements of the zero‐field specific heat show a systematic increase in width of the specific‐heat transition with increasing deformation as well as a small increase inTc. Both &kgr; and the &kgr; variation increase with increasing plastic deformation. The analysis method allows the specific‐heat data of the mixed state to be decomposed in a way consistent with previously reported anisotropy data for niobium.