QJ may refer to: QJ (New York City Subway service), a defunct rapid transit service (1960–1973) ATCvet code QJ (Antiinfectives for systemic use), a veterinary medication class China Railways QJ, a Chinese steam rail locomotive class (built 1956–1988) Quarterly Journal of Austrian Economics, since 1998, by the Mises Institute Quarterly Journal of Economics, since 1886, by Harvard University QJ, a UHF IMTS radio frequency