Back ground: In Ethiopia the proportion of house holds with adequately iodized salt and knowledge and practices on proper utilization of adequatly iodized salt was low to achieve the target for elimination of iodine deficiency disorder. The objectives of this study was to assess the proper utilization of adequately iodized salt and associated factors at house hold level in Asella town, Arsi Zone Ethiopia in 2015. Methods and material:A Cross-sectional study design with multi stage sampling technique was applied to take sample size of 840 HHs. Standard questionnaire with modification and improved iodized salt test kit was used to collect data. Twenty four hour recall period was used to minimize recall bias. Data entered by epi info 3.5.4 and tranfered to SPSS Version 21. Logistic regression model was used to adjust confounders and P-Value <0.05 was considerd to declare significancy.Result: Proportion of HHs with adequately iodized salt was 62.9%. About 76.8% of HHs add salt to their cooking at the end of cooking or right after cooking. Female Sex (AOR = 3.39, 95% CI = 1.07,10.73), Education status with only read and write (AOR = 0.19, 95% CI = 0.05, 0.71), having monthly income ≥2000 ETB (AOR = 2.39, 95% CI = 1.09, 5.01), Being married (AOR = 2.65, 95% CI = 1.24,5.67), Knowing that goitor resulted from iodine deficency (AOR = 9.38, 95% CI = 3.50, 24.89) and having knowledge on IDD and iodized salt (AOR = 4.93, 95% CI = 2.54, 9.58 ) were significantly associated with proper utilization of iodized salt at house hold. Conclusion and Recommendation:Proportion of households with adequately iodized salt was low (not adequate) and significant number of households have improper utilization. Monitoring iodized salt at HH by using test kit and health promotion and communication activites by using different communication methods is important to imprve proper utilization of aduqaute Iodized salt at household level.