The microhardness of glasses of the system 60B(2)O(3)-(40-x)PbO-xMCl(2) and 50B(2)O(3)-(50-x)PbO-xMCl(2) (M = Cd, Pb) was investigated for 20 different compositions over a wide range of applied loads. The microhardness number was found to increase rapidly at lower values of the load, then to increase at a slower rate and finally it attained a constant value above 200 g load. The load dependence of the apparent hardness in the low load region is discussed. The indentation size effect (ISE) on the microhardness is discussed and the load independent true microhardness values are evaluated. The dependence of true microhardness value with increase in mole percentage of PbCl2 or CdCl2 is discussed based on the expansion of the borate matrix. (C) 2005 Springer Science + Business Media, Inc.