Japanese satellite-borne infrared telescope, the Infrared Telescope in Space (IRTS), was successfully launched on March 18, 1995 UT. The IRTS consisted of a 15 cm telescope cooled with superfluid liquid helium and installed onboard the space flyer unit (SFU) spacecraft. The IRTS mission started on March 29, UT and terminated on April 26 UT after liquid helium ran out. The cryogenic system operated as designed and held the telescope and the focal-plane instruments at a stable temperature of 1.9 K for 38 days. Four focal-plane instruments which together covered almost the entire infrared wavelength range observed a sky area of about 2700 deg2 and returned a wealth of new data on a variety of objects, including the zodiacal light, interstellar gas and dust, near-infrared background light and point sources.