A filament stretching rheometer is used to follow the evolution in the tensile force and the flow induced birefringence of a wormlike micelle solution experiencing a uniaxial elongation flow. The experiments are performed using a series of wormlike micelle solutions of cetyltrimethylammonium bromide and sodium salicylate in de-ionized water. The linear viscoelastic shear theology of the wormlike micelle solutions is well described by an upper convected Maxwell model with a single relaxation time. In transient homogeneous uniaxial extension, the wormlike micelle solutions demonstrate significant strain hardening and a failure of the stress-optical, however, no stress-conformation hysteresis is observed. A quantitative fit to the extensional theology of each of the wormlike micelle solution tested is achieved with a FENE-PM model having as few as two relaxation modes. At a critical stress, nearly independent of strain rate, the wormlike micelle solutions filaments are found to fail through a dramatic rupture near the axial midplane. This filament failure is not the result of elastocapillary thinning as is commonly observed in the filament stretching of weakly strain hardening polymer solutions. Instead, the filament failure might stem from the local scission of individual wormlike micelle chains. The energy of wormlike micelle chain scission is calculated to be roughly (4) under bar k(B)T for all the solutions tested, nearly independent of both the imposed extension rate and the concentration of the surfactant and the salt. (C) 2003 The Society of Rheology.