Anticancer drug sensitivity testing using the collagen gel droplet embedded culture drug sensitivity test (CD-DST) on oral squamous cell carcinoma (OSCC) samples beginning from 2010 has been conducted. The present study investigated the effect of adding cetuximab (Erbitux®), a molecularly targeted drug, on anticancer drug activity against clinical OSCC specimens. A total of 25 specimens were obtained from 25 patients with OSCC between October 2013 and December 2017. The present study conducted anticancer drug sensitivity testing for cisplatin (CDDP), 5-fluorouracil (5-FU), cetuximab, three-drug combination, single agent and multi drug combinations, and cetuximab addition to the aforementioned regimens using CD-DST. In addition, the optimum concentration of each drug was evaluated. The overall evaluation success rate of the CD-DST method for OSCC specimens was 84.0% (21 of 25 cases); sensitivity to anticancer drugs and cetuximab could be evaluated. The in vitro efficacy rate of a cetuximab single agent and CDDP + 5-FU (PF) at a cut-off value of 50% was similar to the known clinical response rate. However, at a cut-off value of 50%, the in vitro efficacy of PF + cetuximab was calculated to be 40%, which was higher than the clinical response rate. The CD-DST method could be used to evaluate cetuximab, a molecularly targeted drug. Furthermore, its additive effect on conventional chemotherapy could be evaluated. The CD-DST method is suitable for evaluating and selecting chemotherapy regimens, including molecularly targeted drugs. Future studies are required to generate and evaluate relevant clinical data.