The effect of amount of furniture on the subjective evaluation of spaciousness and estimation of size has been studied in a completely randomized experi-mental design. 90 male architecture students were used as subjects. Two adjacent office rooms, one being standard and the other comparison were used as stimuli. The furniture of the standard room was kept constant throughout the experiments, whereas, that of the comparison room was manipulated as empty, furnished and overfurnished. Each subject assessed both spaciousness and size, the order of which was counterbalanced within each of the experimental groups. According to the results of analysis of variance, the effect of furniture density on spaciousness and size was highly significant.