In this study, the anti-cancer activity of linalool was investigated in MCF-7 breast cancer-bearing mice. Natural killer (NK) and B cell populations in peripheral blood were studied by flow cytometry. The expressions of proliferating cell nuclear antigen (PCNA) and Ki-67 in xenograft tumors were evaluated by immunohistochemistry. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to investigate apoptosis induction in an in vivo model. The results indicated that linalool possesses an inhibitory effect on breast cancer growth in the xenograft model. Linalool reduced B cell counts, but increased NK cell counts in mice peripheral blood. The immunosignals of PCNA and Ki-67 were significantly lower in the linalool treatment group than those of the control group. The TUNEL assay showed that linalool significantly induced apoptosis compared to the control group. The findings of this study provide insight and evidence on the antiproliferative activity of linalool on human breast cancer.