This study investigates the application of unground rice husk ash (URHA) as fine aggregate in mortar. Mortar samples, which typically have 0-50% URHA as the total aggregate volume, is prepared to achieve the green development of construction material industry. Mixtures are designed in accordance with waterto-binder (W/B) ratios of 0.5 and aggregate-to-binder (A/B) ratios of 2.6. A number of indicators for assessment of influence of URHA on mortar are conducted by determination of bulk density, water absorption, length change, compressive and flexural strength. Result shows that compressive strength rises with increases in the percentage of RHA up to 30% replacement. Addition of URHA significantly decreases density but slightly increases water absorption. The analysis results indicate that the utilization of URHA has positively affects the producing green mortar in the future and URHA can be used for low-medium cost material.