The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) is organized into chapters based on body system or condition. Select a chapter below to explore its sections and specific diagnosis codes for the 2025 version.
Certain infectious and parasitic diseases (A00-B99)
Neoplasms (C00-D49)
Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89)
Endocrine, nutritional and metabolic diseases (E00-E89)
Mental, Behavioral and Neurodevelopmental disorders (F01-F99)
Diseases of the nervous system (G00-G99)
Diseases of the eye and adnexa (H00-H59)
Diseases of the ear and mastoid process (H60-H95)
Diseases of the circulatory system (I00-I99)
Diseases of the respiratory system (J00-J99)
Diseases of the digestive system (K00-K95)
Diseases of the skin and subcutaneous tissue (L00-L99)
Diseases of the musculoskeletal system and connective tissue (M00-M99)
Diseases of the genitourinary system (N00-N99)
Pregnancy, childbirth and the puerperium (O00-O9A)
Certain conditions originating in the perinatal period (P00-P96)
Congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
Injury, poisoning and certain other consequences of external causes (S00-T88)
External causes of morbidity (V00-Y99)
Factors influencing health status and contact with health services (Z00-Z99)
Codes for special purposes (U00-U85)
ICD-10-CM codes are hierarchically structured, starting with broad chapters. Each chapter covers a major category of diseases or health conditions, such as "Certain infectious and parasitic diseases" or "Diseases of the circulatory system." Browsing by chapter is a fundamental way to navigate the ICD-10-CM classification and understand its organization.
From here, you can drill down into specific sections and then to individual diagnosis codes, accessing detailed information including official descriptions, coding notes (like Includes, Excludes1, Excludes2), and guidelines essential for accurate medical billing and statistical reporting.