The aim of this study was to describe and analyze the patterns of radiation exposure of contacts of Sudanese patients treated with radioactive 131 I on an out-patient basis and post discharge after high dose 131 I therapy, and also to compare the family members׳ results with dose constraints proposed by the European Commission (EC). Thermoluminiscent dosimeters (Model TLD-100 H) were used to estimate the effective doses for 40 family members of fifteen patients treated with 131 I. The family members wore a TLD in front of the chest for 10 days. The effective dose ranged from 0.23 to 6.74 mSv (mean 1.75 mSv). These findings may be considered when establishing new national guidelines concerning radiation protection and release of patients after a treatment with radioiodine therapy.