It is proposed that the triangular antiferromagnetic &bgr;-structure precedes the triangular antiferromagnetic &agr;-structure observed inYMnO3by neutron diffraction studies at 4.2 K. The experimental observation of the anomalous behavior of the dielectric constant below Ne´el temperature is attributed to the phase transition between &bgr; and &agr; configurations. ©1998 American Institute of Physics.