Basopenia (or basocytopenia) is a form of agranulocytosis associated with a deficiency of basophils.

[2] It is difficult to detect without flow cytometry, because normal levels are so low.

[3] It can be defined as less than 0.01 x 109 / L.[4] Basopenia has been observed in a number of conditions, including after the administration of corticosteroids and in disease states such as chronic urticaria and lupus.

[5] Basophils, which account for a small proportion of the total leukocyte count, are phagocytic.

Heparin, histamine, and serotonin are found in the basophilic granules.