There have been three runs -- in March and November 1993 and October 1994 -- with the JCMT-CSO interferometer, which is a collaborative project with Caltech. In general these were very successful, although the last run was affected by poor weather. The system was used routinely at frequencies above 300GHz, making it the only interferometer in the world currently operating in the submillimetre waveband, and fringes have even been obtained at 490GHz. The observing efficiency and instrumental phase stability have been improved to the point where the sensitivity is now close to theoretical expectations and, under most conditions, the phase variations are dominated by atmospheric fluctuations. Given the complexity of the systems on the two different telescopes, setting up the interferometer is still quite difficult, although the software for taking and analysing data is now rather sophisticated and operation is reasonably reliable. The instrument is therefore not `common-user', but observations are being undertaken on behalf of applicants from the JCMT and CSO user communities.