Orexin receptor 1 (Ox1r) is localized in many brain regions with especially abundant expression in the locus coeruleus (LC). But, its physiological roles have remained unknown. Previous studies have showed that the LC plays an important role in establishing contextual fear memory (Ishida et al. 2002). Also, noradrenergic neurons in LC are known to project to the amygdala that plays critical roles in establishing fear memory (Asan, 1998). We hypothesized that Ox1r in the LC may be involved in the emotional memory. To evaluate this hypothesis, we examined phenotype of Ox1r^-/- using a classical cued and contextual fear conditioning test. We found that Ox1r^-/- mice showed significantly weaker freezing behavior in test session, with normal freezing in the training session. We injected an adeno-associated viral vector carrying Ox1r specifically to noradrenergic neurons in the LC to examine whether expression of Ox1r in the LC can rescue the phenotype. The expression of Ox1r in the LC restored freezing behavior to levels comparable to wild type mice in the test session. These observations suggest that Ox1r in the LC may play an important role in establishing fear memory.