The displacement D and length L of thrust faults associated with lobate scarps on Mercury and Mars are estimated from topographic and planimetric measurements. D ranges from 0.29 to 3.58 km for mercurian thrust faults (n=10) and from 0.27 km to 2.90 km for martian thrust faults (n=13). The D-L relationship between thrust fault populations analyzed on Mercury and Mars is very similar (&ggr;Mercury=6.5¿3.2¿10-3, &ggr;Mars=5.9¿2.0¿10-3), and about an order of magnitude lower than terrestrial thrust faults. The difference is probably dominated by the contrast in tectonic setting between terrestrial thrust faults and those on Mercury and Mars. The similarity in morphology and the D-L relationship of the mercurian and martian thrust faults may be due to the similarity in mechanical properties of the deformed materials and the acceleration due to gravity of the two planets. ¿ 2000 American Geophysical Union