The ability to acquire digitally collected, energy-filtered electron diffraction patterns has permitted the development of fully quantitative methods of pattern analysis based on fitting theoretical calculations to experimental intensities. We have developed a method of extracting accurate low-order structure factor information from zone-axis CBED patterns using an automated pattern matching technique. The feasibility of such an approach has already been established by fitting to simulated data-sets. Results are now presented from pattern matching calculations using energy-filtered Si  zone-axis patterns obtained with a serial EELS detector attached to a Philips EM420 TEM. Fits to patterns at two different sample thicknesses (measured to be 2761 and 4092 Angstrom) are discussed. The results show good agreement with the most accurate Si structure factors obtained from X-ray measurements.