A thermotropic liquid crystalline (LC) polyester containing the 2-butoxyethyleneoxy-1,4-phenylene terephthalate unit (PBEPT) was synthesized and characterized by viscosity measurements, thermogravimetry (t.g.a.), d.s.c. and polarizing microscopy. The polymer exhibited liquid crystallinity in the processing temperature range of poly(ethylene terephthalate) (PET). Blends of PBEPT and PET were prepared. Rheological measurements of the blends were conducted, and compared with data for pure PET, in order to evaluate the effect of the LC polyester on the viscoelasticity of the matrix polymer. Dynamic oscillatory shear, as well as steady shear measurements, indicated a depression of the melt viscosity of PET by 80% caused by the addition of 2-5% of PBEPT.