(3757) 1982 XB is a near-Earth asteroid, about 0.5 kilometers in diameter, that completes one revolution around the Sun about every 2½ years. It was discovered by E. F. Helin at the Palomar Observatory on December 14, 1982. It is an S-type asteroid, meaning it possesses a silicaceous (stony) composition. It is listed as an Amor asteroid (epoch 2014). It has the second lowest designation number among asteroids that are not named, after 3708.