CR-39 tracketch detectors were used for the measurement of ²²² Rn concentration in 24 offices in Nigeria′s oldest university campus in order to estimate the effective dose to the occupants from ²²² Rn and its progeny. The dosimetric measurements were made over a period of 3 months. Questionnaires were distributed and analyzed. The radon concentration ranged from 157 to 495 Bq /m ³ , with an arithmetic mean and standard deviation of 293.3 and 79.6 Bq/ m ³ , respectively. The effective dose to the workers was estimated and this varied from 0.99 to 3.12 mSv/ y, with a mean of 1.85 mSv /y. The radon concentrations were found to be within the reference levels of ICRP.