Introduction: This study intends to determine the relationship between loneliness and internet addiction in students of Hamadan University of medical sciences in 2013.Material and Methods: In this cross-sectional descriptive-analytic study, students of Hamadan University of medical sciences were research population that sample involved 130 people which have been selected through random sampling. To gather the data, Loneliness Scale and Internet Addiction Questionnaire was used as well as demographic variables questionnaire. To analyze the data SPSS was used.Results: The findings revealed the characteristics of the research population as follows: high internet addiction and relatively loneliness. Results showed significant relationship between the internet addiction and age, term and level of education, also factors such as marital status, gender and occupation have no significant relation with internet addiction. Analysis indicated there were no statistically significant differences between loneliness and age, term, level of education, marital status, gender and occupation.Discussion: Due to the relatively high rate of Internet addiction in the study population, the findings will be reported to relevant managers and officials, to be considered in planning future.