Indoor radon was systematically surveyed in the towns of Al Hasahisa and Rufaa in the central part of Sudan. The radon concentrations were measured in 276 measurements, using CR-39 etched track detectors. The radon concentration in the corresponding towns was found to vary from (86 ± 10) Bqm-3 in Al-Hasahisa to (66 ± 8) Bqm-3 in Rufaa. Assuming an indoor occupancy factor of 0.8 and 0.4 for the equilibrium factor of radon indoors, we found that the effective dose rate from 222Rn in the studied towns ranges from (2.18 ± 0.26) to (1.67 ± 0.20) mSv y-1 and the relative lung cancer risk (RRLC) for radon exposure was 1.078 to 1.059% in Al Hasahisa and Rufaa towns respectively. The recorded values of indoor radon concentration in this study are much lower than the radon action level as recommended by ICRP-1993, lower than the new reference level set by WHO and below the action level recommended by the Environmental Protection Agency (EPA). The values of the radon effective dose rate in this survey are slightly larger than the ‘normal’ background level as quoted by UNSCEAR-2000, but way below even the lower limit of the recommended action level as reported by the ICRP- 1993. The reported values of RRLC are almost negligible.