Abstract： Objective To explore the effect of hyperbaric oxygen (HBO) on the tumor growth of human pharyngeal cancer in mouse model.Methods Thirty-two male Balb/c mice were randomly divided into 4 groups:group A or the control group (sacrificed 5 days after tumor loading),group B (sacrificed 10 days after tumor loading),group C (sacrificed 5 days after tumor loading and HBO exposure),and group D (sacrificed 10 days after tumor loading and HBO exposure),each consisting of 8 animals.Following vaccination with the digested pharyngeal cancer Fadu cells in logarithmic phase,the tumor-loaded mice were respectively exposed toatmospheric air and HBO.Then,tumor volume,weight,histopathology and immunohistochemistry were detected for the animals of each group.Results Histopathology of the tumor-loaded mice in each group displayed low-differentiated squamous cell carcinoma.For the animals in group C,tumor mass inhibition rate was 20.13％,and volume inhibition rate was 20.54％.The expression level of fibroblast activation protein-alpha (FAPα) was obviously inferior to that of group A (P ＜ 0.05).For the animals in group D,tumor mass inhibition rate was 13.65％,and volume inhibition rate was 10.30％ and the expression level of FAPα was obviously inferior to that of group B (P ＜ 0.05).Conclusions HBO seemed to have certain effect on the inhibition of tumor growth of human pharyngeal cancer in mice.