This study attempts to develop building blocks using local Brahmaputra river sand. Three types of sand namely: fine, moderately coarse and coarse having fineness modulus (F.M.) of 1.4, 1.8 and 2.5 respectively and ordinary Portland cement (Type-I) were used. For each type of sand three different proportions of cement: sand (1:4, 1:6 and 1:8) were selected. The dimension of the specimens was selected as 250mmx125mmx75mm. After 28 days of water curing the specimens were tested for density, water absorption, and compressive strength. The test results showed that the density of blocks was highest for fine sand, medium for moderately coarse sand and lowest for coarse sand. The water absorption of the blocks for coarse sand was higher than others while the compressive strength of the blocks was highest for coarse sand, medium for moderately coarse sand and lowest for fine sand. It was also revealed that the sand-cement blocks made with moderately coarse sand at 1:6 mix proportions showed the best combination in terms of density, water absorption, compressive strength and cost.