An online version of the World Health Organization's International Classification of Diseases, Ninth Revision coding manual is available at ICD9Data.com and CDC.gov as of 2015. The ICD-9 Clinical Modification, or ICD-9-CM, based on the ICD-9, is the official system the United States uses to assign diagnoses and hospital procedure codes.
The ICD-9 is no longer available in print. The ICD-9-CM, which the WHO updates annually, gives more detailed morbidity data than the ICD-9.
The U.S. Department of Health and Human Services requires all health care plans, providers and clearinghouses to use ICD-10-CM/Procedure Coding System as of Oct. 1, 2015. A free transition site is available at ICD10Data.com, which is compatible with mobile devices.