The fracture behaviour of binary mixtures of low molar mass linear polyethylene (L2.5 : <(M)over bar (w)>, = 2500 g mol(-1), <(M)over bar (w)>/M(n) = 1.15) and higher molar mass linear and branched polyethylenes has been studied. The average tie-chain concentration of the different samples has been indirectly estimated. It was found that the true stress at fracture, fracture strain and fracture energy increased with the calculated average tie-chain concentration for all the binary blends. For the binary mixtures of L2.5 and the higher molar mass linear polyethylenes, there is no unique relationship between true stress at fracture and calculated average tie-chain concentration, suggesting that segregation of L2.5 is an important factor determining the strength of these samples. The fact that the L2.5/branched polyethylene blends with intimately mixed constituents exhibited a higher strength than the L2.5/linear polyethylene mixtures, with a distinct segregation of L2.5, could be explained as being due to the higher average tie-chain concentration in the former blends.