The antiviral activity of 13(E)-labd-13-ene-8alpha,15-diol (1), isolated from Brachyglottis monroi, was examined against human rhinovirus 2 (HRV2) and 3 (HRV3), and the anticancer activity on human cancer cells (A549 and Hep2). Compound (1) showed strong anti-HRV2 and HRV3 activity with a 50% inhibitory concentration (IC(50)) of 2.68 and 0.87 microg/mL, respectively, and a 50% cytotoxicity concentration (CC(50)) of 59.45 microg/mL. Ribavirin only showed anti-HRV3 activity with an IC(50) of 30.48 microg/mL and a CC(50) > 100 microg/mL. The addition of compound (1) to HRV-infected HeLa cells directly reduced the formation of visible cytopathic effect (CPE) and it directly interacted with HRV particles. Furthermore, A549 and Hep2 cells incubated with 32 microg/mL of compound (1) for 48 h exhibited antilung and antilaryngeal cancer activities, with a viability of less than 50%. These results suggest that compound (1) may be used as a potential antiviral and anticancer agent.