The objective of this study was to determine the effect of colour on the perception of tree forms and the effects of personal characteristics of the participants on their preferences. The students of science studies, medical science and social science of Duzce University, Turkey, participated in the study (n=159). The participants were asked to evaluate 5 different tree forms which were drawn by hand and coloured with 8 different colours by semantic differential method. According to the results obtained, pyramid-formed trees were preferred most and colour had a strong effect on the preferences of tree forms. Bright green trees were found to have the highest visual quality while blue-coloured trees the highest strength. Again, the results obtained in this study indicate that personal characteristics are effective on preferences of tree forms and colours.