Résumé : The measurement of the correlation between the transverse spin components of τ+ τ- pairs collected during 1992 to 1994 with the DELPHI detector at LEP1 is presented. A value CTT = 0.87 ± 0.20 (stat.) +0.10-0.12 (syst.) was obtained for the correlation parameter, in agreement with the Standard Model expectation. © 1997 Published by Elsevier Science B.V.