NGC3389 is a spiral galaxy in the constellation of Leo. Its velocity with respect to the cosmic microwave background is , which corresponds to a Hubble distance of . However, 24 non-redshift measurements give a closer mean distance of . 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.
NGC 3389, Messier 105, and NGC 3384 are listed together as Holm 212 in Erik Holmberg's A Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems, published in 1937.
According to A. M. Garcia, NGC 3389 is a member of the NGC 3338 Group (also known as LGG 214). In addition to NGC 3338, this galaxy group includes at least three other galaxies: NGC 3346, UGC 5832, and MRK 1263.
Two supernovae have been observed in NGC 3389.