This group comprises substances used for the treatment of cardiovascular conditions.
Drugs used for the treatment of hypertension are classified in C02 - Antihypertensives, C03 - Diuretics, C07 - Beta blocking agents, C08 - Calcium channel blockers, and C09 - Agents acting on the renin-angiotensin system. For the classification of combination products of antihypertensives from different ATC groups, the following ranking should be used, from higher to lower precedence: C09, C07, C08, and C03.

This group comprises combinations of beta blocking agents, thiazides and other diuretics. Different thiazides and diuretics may occur at each 5th level.
Combinations with other agents in addition, are classified at separate 5th levels using the 50-series.