This study examined the predictive power of sex roles and attachment styles on loneliness. A total of 188 undergraduate students (114 female, and 74 male) from Gazi University completed the Bem Sex Role Inventory, UCLA Loneliness Scale, and Relationship Scales Questionnaire. Hierarchic Multiple Regression analysis and t-test were used to test hypotheses. Results indicated that there was no gender difference in loneliness. Also results revealed from Hierarchic Multiple Regression analyses that loneliness was predicted by fearful attachment, secure attachment, and masculinity, respectively in total samples. Additional analysis indicated that predictive power of masculinity was significant on loneliness only for men. (Contains 2 tables.)