Objectives: 1) To determine the sensitivity of modified inclusion testfor screening alpha-thalassemia 1 trait 2) To find the prevalence ofalpha-thalassemia 1 in the first region of the Royal Thai army 3) To compare thecost-effectiveness ratio in term of cost per one case of alpha thalassemia 1 detectedbetween hemoglobin H inclusion test and PCR test Design: Diagnostic test Setting: The First region of the Royal Thai Army Participant: Asymptomatic people who agree to participate in thalassemiascreening program. Outcome Measurement: The main outcome of modified hemoglobin h inclusion testand PCR test are positive and negative. Results: The value of modified hemoglobin H inclusion test are sensitivity =81%, specificity = 98%, accuracy = 96%, positive predictive value = 85%, negativepredictive value = 98% likelihood ratio if test positive = 44.8, likelihood ratio iftest negative = 0.2 and the prevalence =11.5%.