This study was carried out in order to analyse the ultrasound technique as an alternative form of assessing the structural state of different wooden buildings. This work studies the effect and relative importance of measurement direction and moisture content on ultrasound speed in wood. Radiata pine wood samples were subjected to 1 MHz longitudinal ultrasound pulses. A 22 factorial design was run in a completely random experiment. Measurement direction was the significant factor, as shown by the analysis of variance, explaining 95% of total ultrasound velocity variability. Average tangential and radial propagation speeds were between 0% and 15% moisture content, 1644 m/s and 2130 m/s, respectively. The results of this study showed that wave propagation direction is the most important factor during wood structure ultrasound evaluation. Future studies with combined planes are underway.