AIM:To observe the clinical effects of botulinum toxin A(BTXA) injection guided by high-frequency ultrasound in the treatment of restrictive strabismus in thyroid associated ophthalmopathy.METHODS: Thirty-two patients with restrictive strabismus in thyroid associated ophthalmopathy were recruited in clinical study.Under the guide of high-frequency B ultrasound diagnostic apparatus, BTXA was injected into the extra-ocular muscles.The changes of the degree of and strabismus diplopia were observed after therapy.RESULTS: In all eyes of 32 patients,the strabismus and diplopia were lessened in different degrees after repeated injection with botulinum toxin A in the affected extra-ocular muscles for 2 to 4 times. The total apparent rate was 47%,effective rate was 44%, ineffective rate was 9%.CONCLUSION: BTXA injection guided by high-frequency ultrasound technique is accurate positioning method in the treatment of restrictive strabismus in thyroid associated ophthalmopathy. It is an effective therapy to lighten the contraction of extra-ocular muscles remission of diplopia symptom and strabismus degree.