The paper, part of a general investigation of mixing and chemical reaction in turbulent jets, concerns the length of non-premixed turbulent jet flames in a stationary environment. Experimental results for the turbulent flame length of chemically reacting jets in water show both increasing and decreasing mean flame length with increasing Reynolds number in the transition regime between laminar and fully developed turbulent flow, depending on the equivalence ratio for the reaction. The asymptotic limit of this transition regime, at which the flame attains its Reynolds-number-independent length, is established at Reynolds number 3000. Above this limit, the mean flame length depends linearly on the reaction equivalence ratio. Fluctuations in the flame length are found to be nearly periodic and approximately equal to the local jet diameter at the flame tip for all equivalence ratios and all Reynolds numbers above 3000, indicating that turbulent flame length is inherently unsteady at the largest local scale in the flow.