We investigated the sensitizing effects of AK-2123 (Senazole) on the interaction of radiation, cisplatin and hyperthermia under aerobic conditions in the rat yolk sac cell line NMT-1R in vitro. The effects were assessed by clonogenic assay. A cytotoxic effect of AK-2123 after 24 hours exposure was observed as a function of the dose. For NMT-1R cells, the ID70 of AK-2123 was 400 micrograms/ml for 24 hours exposure, which was employed for subsequent combined treatments. Although a statistically significant increase in the G1 cell fraction was observed after AK-2123 treatment with a dose of ID70 (p = 0.02) no enhancing effect of AK-2123 on radiation, cisplatin or heat response curves was detected under aerobic conditions in vitro.