2006 ICD-9-CM Volume 1 Diagnosis Codes Home > Diseases Of The Circulatory System 390-459 > Hypertensive Disease 401-405 > ICD-9-CM Diagnosis 401 Essential hypertension 401 is a non-specific code that cannot be used to specify a diagnosis ICD-9-CM Diagnosis 401.0 Malignant essential hypertension 401.0 is a specific code that can be used to specify a diagnosis ICD-9-CM Diagnosis 401.1 Benign essential hypertension 401.1 is a specific code that can be used to specify a diagnosis ICD-9-CM Diagnosis 401.9 Unspecified essential hypertension 401.9 is a specific code that can be used to specify a diagnosis 401.9 contains 10 index entries