Abstract： Objective To understand the prevalence of internet addiction disorder(IAD)and explore its relationship with suicidal tendency of undergraduates.Methods A total of 1517 undergraduates were investigated by using Internet Addiction Scale(IAS),Beck Hopelessness Scale(BHS)and self-made questionnaire.Results The prevalence of lAD was 14.8％.Males,single child,and those at the second grade,with poor performance or higher family income were at a higher risk of internet addiction(P ＜ 0.01).There was significantly positive correlation between internet addiction and suicidal tendency in undergraduates(x2 =76.30,P ＜ 0.01,r =0.40).The risk of suicidal tendency was significantly increased in the high internet addiction score group(OR =12.29,95 ％ CI 6.33 to 23.84).Conclusion Higher prevalence of IAD was found in the undergraduates,which could contribute to the increasing suicide.