The Barstow trilateration network spans late Cenozoic right-lateral strike-slip faults in the Mojave Desert block in southern California. The network has been surveyed four times between 1979 and 1984. A marginally significant increase of 0.47¿0.18 μrad in fault-parallel right-lateral shear strain occurred in 1980. This increase may reflect random error in measurement since more than half of it is due to changes in only three lines, while other lines favorably oriented to detect shear show no change. The overall rate of fault-parallel shear is 0.06¿0.05 μrad/yr, a rate which does not differ significantly from zero. The maximum shear strain rate is 0.08¿0.05 μrad/yr, oriented N21¿W¿17¿.