To investigate the dimensional properties of 1$ imes$1 rib knitted fabrics, cotton and polyester/cotton knitted fabrics with various loop lengths were prepared. Course density, rib density, stitch density, thickness and weight per unit area of sample fabrics were measured at dry and wet relaxed states, and the values of K1-4 and bulkiness, were calculated and inspected. As the results of the study, it was noted that cotton knitted fabrics were reached to fully-relaxed state by wet-relaxation treatment, at 7$0^{circ}C$ for 24hrs with the K1 valus of 68.4 at that state, while polyester/cotton knitted fabrics to fully-relaxed state by tumble drying at 7$0^{circ}C$ for 2hrs after wet-relaxation treatment at 7$0^{circ}C$ for 24hrs with K1 valus of 65.5. Under fully-relaxed state, K4, the ratio of course density and rib density became almost constant; K4=1.5 for cotton knitted fabrics and 1.3 for polyester/cotton knitted fabrics. Relaxation treatment increases thickness and bulkiness. Those of cotton knitted fabrics increase more than those of polyester/cotton knitted fabrics. Under fully-relaxed state, area shrinkage ratio of cotton knitted fabrics was larger than that of polyester/cotton knitted fabrics; cotton knitted fabrics reached about 25% and polyester/cotton knitted fabrics about 15%.