The exclusive process -p-p has been measured at 90°c.m. with an incident pion momentum of 9.9 GeV/c. We present data on the angular dependence of the decay - 0. We observe a strong azimuthal dependence in the decay in the c.m. helicity frame of the. Such an azimuthal dependence is not compatible with SU(6) valence-quark perturbation calculations.