Caryophyllene oxide (CRYO) is a sesquiterpenoid found in numerous plants. It has shown various biomedical properties including anti-inflammatory, antifungal, and immunomodulatory activity. In our previous study, Neolitsea (N.) hiiranensis and its derived CRYO inhibited several aspects of adaptive immune responses in vitro, including T-cell differentiation, IFN-γ production, and Th1-assocaited genes. However, it’s still unknown whether Neolitsea hiiranensis and CRYO modulates Th1-related immune disorders in vivo, such as delayed type hypersensitivity (DTH) which antigen-activated Th1 cells and macrophage are involved in. The aim of this study is to discover the immunomodulatory effects of N. hiiranensis and CRYO in Th1-mediated immune disorders. 5-week-old male BALB/c mice were separated into the following groups (four mice per group): (1) naïve group; (2) vehicle-treated (saline) plus ovalbumin (OVA)-sensitized and challenged group; and (3) leaves extracts of N. hiiranensis (5 and 20 mg/kg) as well as CRYO (5 mg/kg) treatment before OVA sensitization and challenge by intraperitoneal injection. To induce local DTH reactions, the hind footpads of all mice challenged subcutaneously with OVA. Footpad swelling was measured and for further pathological investigation. We also examined the genotoxic effects of CRYO by evaluating micronuclei formation in mammalian cells (chromosomal damage). Our results demonstrated the leaves extract of N. hiiranensis and CRYO significantly ameliorated inflammatory reactions associated with DTH, including the footpad swelling, infiltration of IFN-γ+ cells and macrophages. Administration of CRYO, significantly systemically suppressed the serum level of OVA-IgM and OVA-IgG2a and IFN-γ production by splenocytes in vivo. CRYO (0.2-1 mg/kg) suppressed Th1-related T-box transcription factor (T-bet) mRNA expression, while Th2-related transcription factor (Gata-3) was not altered in vivo. According to the in vitro micronucleus assay, CRYO didn’t show genotoxicity in vitro. Collectively, CRYO may have beneficial immunomodulatory effects to ameliorate Th1-mediated delay-type hypersensitivity and to balance the Th1/Th2 antigen-specific immune responses.