OBJECTIVE To investigate the clinical effect of Quxie Capsule (QXC) in subsequent therapy for post-operational colorectal cancer. METHODS By the scheme matched to the requirement of randomized controlled trial, 44 patients chosen from 48 patients with colorectal cancer at post-operational period (with 2 dropped out and 2 loss of follow-up) were assigned into two groups (A and B) according to randomiced block design and received intervention treatment with QXC and placebo, respectively, which started after terminating the post-operational adjuvant treatment and lasted for 6 months. Out of the 44 patients, 28 were of stage II (15 in Group A and 13 in Group B) and 16 of stage III (8 in Group A and 8 in Group B). The relapse-metastasis (R-M) rate, median time of R-M, changes of symptoms, Karnofsky (KPS) score and immune function before and after intervention, as well as the safety of QXC were observed. RESULTS The follow-up study till April 2007 showed, the 1-year, 2-year and 3-year R-M rate in Group A was 0%, 0% and 50%, and in Group B was 9.5%, 18.2% and 50.0%, respectively, showing insignificant difference between the two groups (P >0.05). Difference in median time of R-M between the two groups (31.5 +/- 7.8 months vs 19.0 +/- 13.9 months) also showed no statistical significance (P >0.05). However, the symptoms and KPS score in Group A were better obviously (P <0.05), with improvement in B lymphocyte (P <0.05) superior to that in Group B. No obvious adverse reaction to QXC was found. CONCLUSION QXC might be effective in delaying the R-M of colorectal cancer, but the ultimate confirmation only could be obtained through 1 to 2 years observation. Post-operational intervention with QXC in patients with colorectal cancer could apparently improve the quality of life and raise the immune function of patients, it is safe and might have some clinical significance in preventing the R-M of cancer.