NGC 3389 is a spiral galaxy in the constellation of Leo. Its velocity with respect to the cosmic microwave background is 1,651±24 km/s, which corresponds to a Hubble distance of 79.4 ± 5.7 Mly (24.35 ± 1.74 Mpc). However, 24 non-redshift measurements give a closer mean distance of 71.70 ± 3.01 Mly (21.983 ± 0.924 Mpc). It was discovered by German-British astronomer William Herschel on 11 March 1784. It was also observed by John Herschel on 23 March 1830, causing it to be listed a second time in the New General Catalogue as NGC 3373.