The influence of order and the order-disorder transformation for copper-gold alloys on friction was determined in vacuum. The copper-gold alloys contained 10, 25, or 50 atomic percent gold. The latter two alloys are the compounds Cu3Au and CuAu. Both Cu3Au and CuAu exhibit ordering, while the 10 atomic percent gold in copper does not. Friction experiments were conducted in vacuum (10 sub -10 mm Hg) with a hemispherical rider specimen of the copper-gold alloy sliding on itself or 440-C stainless steel. The specimens were examined under loads of 1000 grams, sliding speeds to 880 centimeters per second, and temperatures to 400 C. The results of these studies indicate lower coefficients of friction for the alloys Cu3Au and CuAu in the atomically ordered state than for these alloys in a disordered state. The 10-atomic-percent- gold alloy, which does not become ordered, did not reflect any marked changes in friction when examined under conditions similar to those for Cu3Au and CuAu.