4-Amino-imidazoquinoline compounds and use thereof are disclosed. The compounds of the invention are Toll-like receptor 7 (TLR7) and TLR8 dual agonists, which exhibit activities in inducing IL-12 and IP-10 expression without over-inducing IL-6. The TLR 7/8 dual agonists are potentially useful medications as immune response modifiers. Use of a compound or salt thereof according to the invention in the manufacture of a medicament for treating a disease or a condition wherein activation of TLR7 and/or TLR8 provides a benefit in a subject in need thereof is disclosed. A compound or a pharmaceutical composition for use in treating a viral infection, cancer, and/or an allergic disease, or for use in activating immune responses that are effective against a viral infection, a tumor, and/or an allergic disease in a subject in need thereof is also disclosed.