The activity concentrations of primordial radionuclides(40K, 226Ra and 232Th) in fivedifferent types of commonly used building materials in southwestNigeria were measured using a low-background NaI(Tl) detector coupledto an IBM-compatible multichannel analyzer. The highest mean concentrationof 40K, which was 887.5 ± 101.3 Bq.kg–1, was obtainedin gravel. Also, the highest mean concentrations of 226Raand 232Th were obtained, respectively, in sand and brick samples.The lowest mean concentrations of 40K, 226Raand 232Th, respectively, were obtained in brick and cementsample. The annual gonadal effective dose (AGED) and other radiologicalparameters were estimated from the activity concentrations of theradionuclides. The highest mean values of the AGED and radium equivalentactivity concentration obtained were 359.1 μSv.y–1 and110.9 Bq.kg–1, respectively. All these radiological parameterswere below the maximum permissible levels recommended for safe useof materials in building construction. It can therefore be concludedthat these materials do not pose any radiological hazard to thedwellers of buildings constructed with them.