Caesalpinia sappan L. (C. sappan) has been used in Oriental medicine as an antitumor agent. The present study shows the effects of the chloroform extract of C. sappan on cell death in head and neck cancer cell lines. The viability of HNSCC4 and HNSCC31 cells (head and neck cancer cell lines) was noticeably decreased compared to that of HaCaT cells (control group) in the presence of chloroform extract. No significant difference was observed in the viability of HNSCC4 and HNSCC31 cells when compared with HaCaT cells in the presence of n-butanol, methanol, and water extracts. Exposure to the chloroform extract of C. sappan resulted in an increase in the Sub-G1 phase of the cell cycle and condensation and shrinkage of nuclei in the HNSCC4 and HNSCC31 cells. The levels of p53 and p21WAF1/CIP1 were also increased in the HNSCC4 and HNSCC31 cells. The results suggest that the chloroform extract of C. sappan may increase cell death in the HNSCC4 and HNSCC31 cells, which is linked to increased cellular levels of p53 and p21WAF1/CIP1.