Objective: To determine the maximum tolerated dose(MTD), dose-limiting toxicity(DLT) and efficacy of sorafenib in combination with FOLFOX4(oxaliplatin/leucovorin(LV)/5-fluorouracil) as first-line treatment for advanced gastric cancer, we performed a phase I dose-finding study in nine evaluable patients with unresectable locally advanced or metastatic gastric cancer or gastroesophageal junction adenocarcinoma. Methods: According to modified Fibonacci method, the design of this study was to guide elevation of the sorafenib dosage to the next level(from 200 mg twice daily to 400 mg twice daily and then, if tolerated, 600 mg twice daily). If the patient achieved complete response(CR), partial response(PR) or stable disease(SD) after eight cycles of treatment, combination chemotherapy was scheduled to be discontinued and sorafenib monotherapy continued at the original dose until either disease progression or unacceptable toxicity. Results: In sorafenib 200 mg twice daily group, DLT was observed in 1 of 6 patients, and in 400 mg twice daily group, it was observed in 2 of 3 patients. Seven of 9(77.8%) evaluable patients achieved PR, with a median overall survival(OS) of 11.8 [95% confidence interval(CI): 8.9-14.7] months. Common adverse effects include hand-foot syndrome, leukopenia, neutropenia, anorexia, and nausea.Conclusions: Twice-daily dosing of sorafenib 200 mg in combination with FOLFOX4 was proven effective and safe for the treatment of advanced gastric cancer, and could be an appropriate dosage for subsequent phase II clinical studies. Objective: To determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT) and efficacy of sorafenib in combination with FOLFOX4 (oxaliplatin / leucovorin (LV) / 5-fluorouracil) as first-line treatment for advanced gastric cancer, we performed a phase I dose-finding study in nine evaluable patients with unresectable locally advanced or metastatic gastric cancer or gastroesophageal junction adenocarcinoma. Methods: the design of this study was to guide elevation of the sofenfen dosage to the next level (from 200 mg twice daily to 400 mg twice daily and then, if tolerated, 600 mg twice daily). If the patient achieved complete response (CR), partial response (PR) or stable disease (SD) after eight cycles of treatment, combination chemotherapy was scheduled to be discontinued and sorafenib monotherapy continued at the original dose until either disease progression or unacceptable toxicity. Results: In sorafenib 200 mg twice daily group, DLT was obse Seven of 9 (77.8%) evaluable patients achieved PR, with a median overall survival (OS) of 11.8 [95% confidence] were found in 1 of 6 patients, and in 400 mg twice daily group, it was observed in 2 of 3 patients Common adverse effects include hand-foot syndrome, leukopenia, neutropenia, anorexia, and nausea. Conclusions: Twice-daily dosing of sorafenib 200 mg in combination with FOLFOX4 was proven effective and safe for the treatment of advanced gastric cancer, and could be appropriate dosage for subsequent phase II clinical studies.