The present study aimed to investigate changes in cellular immune function and regulatory T cells (Tregs) in patients with hepatocellular carcinoma (HCC) prior to and following transcatheter arterial chemoembolization (TACE) and their clinical significance. The proportion of CD4+ and CD8+ T cells and Tregs in the peripheral blood between healthy volunteers and patients with HCC were detected by flow cytometry prior to (1 day) and one month following TACE. The level of interleukin (IL)‑35 in the peripheral blood was examined by ELISA. In the peripheral blood of patients with HCC, the proportion of CD4+ T cells in the total T lymphocytes was significantly lower compared with that of healthy volunteers (26.71 ± 5.57, vs. 34.74 ± 2.86%; P<0.05) and the ratio of CD4+/CD8+ T lymphocytes in patients with HCC was lower compared with that of healthy adults prior to TACE (1.03 ± 0.14, vs. 1.68 ± 0.16, P<0.05). The ratio markedly increased following TACE treatment (30.52 ± 4.19, vs. 1.29 ± 0.14). The percentage of CD4+CD25+ Treg cells in the total CD4+ T cells isolated from the patients with HCC was markedly higher compared with that of healthy adults prior to TACE (11.12 ± 3.58%, vs. 4.98 ± 1.45%, P<0.05) and it was significantly decreased following TACE (7.58±2.65%; P<0.05). No statistically significant difference in the expression of IL‑35 was detected prior to or following TACE in patients with HCC and healthy adults (369.66 ± 95.53, 352.28 ± 107.50 and 316.24 ± 89.21 pg/ml, respectively). The level of AFP, an oncofetal protein of ~72 kDa, which is produced by normal gastrointestinal cells, yolk sac cells and fetal hepatocytes immediately following birth, was increased in patients with HCC (1674 ± 1649 ng/ml) and was significantly decreased following TACE (827 ± 981 ng/ml). Treg cells changed in positive correlation with the change of AFP, with a correlation coefficient of 0.401. TACE markedly improved the immune function of patients with HCC.