Samples held at pressures up to 260 kilobar in a diamond anvil pressure cell have been heated to very high temperatures by means of a laser beam introduced through one of the transparent diamond anvils. A 7 J pulsed ruby laser is able to produce temperatures as high as 3000°C in a high pressure sample. A 60 W cw YAG laser is able to produce sustained temperatures up to 2000°C. An optical pyrometer has been used in the latter case to measure the brightness temperature with an accuracy of ±50°C. The ruby laser has been successful in directly converting graphite to diamond; the YAG laser has made it possible to show that (Fe,Mg)2SiO4disproportionates to (Fe,Mg)O plus SiO2(stishovite) at pressures in excess of 200 kilobars and temperatures above 1000°C.