Five new modified eremophilane-type sesquiterpenes (1-5), including three norsesquiterpenes (1-3), and one new monoterpene (6) were isolated from the aerial parts of Parasenecio deltophylla. Their structures were established on the basis of HRMS and NMR methods. The cytotoxicity of compounds 1-4 and 6 against selected cancer cell lines, including human promyelocytic leukemia (HL-60) and human hepatoma (Hep-G2), was evaluated. Antioxidant activities of these compounds were assessed by ABTS and DPPH methods.