Objective: To study the effects of acetaminophen (ACE) combined with radiation on the progeny of the human glioma cell line SHG-44, and to investigate if ACE may be an useful therapeutic radiosensitivity agent in the treatment of recurrent human glioma. Methods: A randomized, controlled experiment, was performed at the Department of Radiology Laboratory, the First Hospital Affiliated to Soochow University, between September 2004 and January 2006. Brain glioma SHG-44 cells were divided into three groups: SHG-44, SHG-44-10, and SHG-44-10 + ACE cells groups. The SHG-44-10 cells group was irradiated with dose of 10 Gy by a linear accelerator (6 MVX). It was passaged for 15 generations and cultured in RPMI-1640 culture media. Then SHG-44-10 + ACE cells group was treated with ACE. Measures: Community re-double time, mean lethal dose (DO), extrapolation number (N), fraction surviving fraction irradiated by 2 Gy dose (SF2), quasi-threshold dose (Dq), and cell cycle. Results: The SF2 of the SHG-44, SHG-44-10, and SHG44-10 + ACE cells groups were 70.8%, 80.6% and 45.2%, respectively, with significance (P = 0.040). The SHG-44-10 and SHG-44-10 + ACE cells groups were irradiated with 8 Gy. After 12 hours, the G2/M ratio of the SHG-44-10 and SHG-44-10 + ACE cells groups were indicating significantly higher ratio compared to pre-irradiated groups (P<0.01). After 24 hours, the G2/M ratio of the SHG-44-10 cells group decreased rapidly, while the ratio of the SHG-44-10 + ACE cells group still maintained in high level. Conclusion: In the present study, Subtoxic dose of ACE increased the radiosensitivity of the progeny of irradiated human glioma cell. ACE may be an useful radiosensitivity agent in the treatment of recrudescent human malignant glioma.