Hexabromocyclododecane was assessed for primary eye irritation with New Zealand White rabbits (3/sex) administered 100 mg of test material in the conjunctival sac of the right eye. Treated unwashed eyes were examined at 24, 48, and 72 hours, and at 7 days. Eye irritation scores derived by the Draize method were indicative of no irritation. A primary skin irritation study was conducted with similar groups of rabbits exposed to 500 mg of test material applied to the back of each rabbit and occluded for 4 hours. Test sites were then washed and examined for irritation at 4, 24, 48, and 72 hours. No evidence was seen of primary skin irritation (mean score = 0.1). Acute dermal toxicity was assayed with rabbits (2/sex) administered doses of 20,000 mg/kg to abraded and intact dorsal skin. Test sites were occluded for 24 hours, then uncovered and washed with tap water. Observation for 14 days revealed no mortalities, but body weight gain was decreased and diarrhea was noted in 1 treated rabbit/sex. Charles River CD strain rats (5/sex) were administered oral doses of 10,000 mg/kg of test material suspended in corn oil by gavage (volume = 20 ml/kg bw) and observed for 14 days. No deaths occurred. Corneal opacity and ptosis were seen in males; diarrhea and hypoactivity were noted in females. Charles River CD rats (3/sex) were exposed to 202.14 mg/L of the test material as dust over a 4 hour exposure period. Slight dyspnea was noted during the exposure period, but no other adverse effects were seen.