NGC 3733 is an intermediate spiral galaxy in the constellation of Ursa Major. Its velocity with respect to the cosmic microwave background is , which corresponds to a Hubble distance of . Additionally, nine non-redshift measurements give a farther mean distance of . It was discovered by German-British astronomer William Herschel on 14 April 1789.
NGC 3733 has a possible active galactic nucleus, i.e. it has a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars.
According to A. M. Garcia, NGC 3733 is part of the NGC 3898 group (also known as LGG 250). This galaxy group has nine members, including NGC 3756, NGC 3794, , , , NGC 3898, NGC 3982, and .
One supernova has been observed in NGC 3733: