Based on a clinical differential effect of the action of a new hypoxic cell radiosensitizer, AK-2123 (a 3-nitro-1,2,4-triazole), on locally advanced cervix cancer (Stage II-B and III-B), a Phase I/II clinical trial has been carried out on 80 consecutive patients. They were intratumorally injected with AK-2123, wt 1% and 2%, 30 min before the delivery of external radiation therapy. The short-term effects show that exophytic types of lesions respond far better than endophytic types and AK-2123 may be replacing intracavitary radium for exophytic Stage II-B cervix cancer as the standard therapy for this neoplasm in our patients. Treatment is well tolerated and no neurological toxicity has been noted.