A randomized controlled trial was carried out on 38 pharyngeal and 59 laryngeal previously untreated cancers to evaluate the effects of adjuvant immunochemotherapy using 5-FU with and without OK-432. After each fundamental therapy, 5-FU was given orally at a dose of 200-300 mg/day for more than a year. OK-432 was intracutaneously administered at a dose of 5KE once a week for more than a year. Three-year survival rates and disease-free intervals were estimated for the two groups. In cases of pharyngeal cancer, the 3-year survival rate was 58% in both groups and the disease-free interval rates for up to 3 years after the fundamental therapy was 49% in the OK-432 + 5-FU group and 52% in the 5-FU group. These results showed no statistically significant difference. In laryngeal cancers, the 3-year survival rate was 96% in the OK-432 + 5-FU group and 82% in the 5-FU group. These results also showed no statistically significant difference. The disease-free interval rates were 87% in the OK-432 + 5-FU group and 64% in the 5-FU group, revealing a statistically significant difference (p less than 0.1). This suggests that OK-432 is more effective in producing a higher survival rate in cases of laryngeal cancer.