Objectives: This study was conducted to assess whether the radiation exposure levels of Omani family members of thyrotoxic patients, if treated with radioiodine therapy as outpatients, are within the international and local radiation dose limits in order to allow them to be treated as outpatients. Methods: The study included 86 family members of 22 self-dependent thyrotoxic patients (29 children ≤ 16 yrs and 57 adults including 11 spouses and 8 parents). The mean age of the family members was 26.6 years (range 17 months - 75 years).They were treated with 131I as outpatients and monitored for 10 days in 2007-2008 for radiation exposure using thermoluminescent dosimeters (TLDs). The mean administered activity of 131I to patients (±SD) was 610 ±79MBq in the range 520-862 MBq. Oral and written radiation safety instructions were given to patients and family members before leaving the hospital. Results: The radiation doses received by family members were less than the annual recommended dose limit for general public of 1mSv, except for four children aged 19 months, 12, 13 and 15 years, who received radiation doses of 2.9, 1.2, 1.2 and 1.2 mSv respectively. Conclusion: In view of the low radiation doses received by the family members, we recommend treating thyrotoxic patients undergoing radioiodine therapy with administered activities up to 800 MBq as outpatients.