[en] A new measurement of the ratio R = sigmasub(L)/sigmasub(T) of longitudinal and transverse structure functions in neutrino interactions on iron between 30 and 190 GeV neutrino energy is reported. The result is given as a function of the scale parameter x and the inelasticity ν of the interaction. The average value is R = 0.10 +- 0.07 around ν approx. equal to 50 GeV and is in accordance with a prediction from the QCD theory. (orig.)