Hepatocellular carcinoma (HCC) is the 6th prevalent cancer and the 4th leading cause of cancer-related deaths all over the world. A major challenge for sorafenib, the standard chemotherapeutic agent in HCC treatment, is the chemo-resistance. This study was conducted to evaluate the role of dantrolene as a possible antineoplastic agent in HCC, and in chemo-sensitization of sorafenib via targeting Ca+2/PI3K pathway. HCC was induced in rats using a single dose of diethylnitrosamine (DENA) (200 mg/kg, ip), followed by phenobarbital sodium (0.05%) in drinking water for 18 weeks. At the end of the 18th week, rats were allocated into 4 groups (10 rats/each), one group was left without treatment (DENA group) and the other three groups were treated with either sorafenib, dantrolene, or their combination for further 4 weeks. One day after the last injection, serum and liver tissues were collected. Liver tissue p53, VEGF, MMP-9, Cyclin D1, PI3K, and, serum AFP were assessed using immunoassay. Hepatic and serum Ca+2 were also computed. Furthermore, Ki-67 was assessed immunohistochemically. Dantrolene exhibited synergistic effect when used in combination with sorafenib compared to either drug alone (p <0.05) through decreasing p53, VEGF, MMP-9, Cyclin D1, and Ki-67. In addition, dantrolene was evidenced to have an inhibitory effect on Ca+2/PI3K pathway that mediates its antineoplastic action when used alone or in combination with sorafenib. Dantrolene exerted antineoplastic effect as well as augmented sorafenib antineoplastic activity via the intervention of Ca+2/PI3K pathway, manifested by ameliorating angiogenesis, apoptosis, proliferation and metastasis.