All the proteins of the albumin family are water-soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Albumins are commonly found in blood plasma and differ from other blood proteins in that they are not glycosylated. Substances containing albumins, such as egg white, are called albuminoids.

Serum albumin is the main protein of human blood plasma. It binds water, cations, fatty acids, hormones, bilirubin, thyroxine (T4) and pharmaceuticals (including barbiturates): its main function is to regulate the colloidal osmotic pressure of blood.

A number of blood transport proteins are evolutionarily related, including serum albumin, alpha-fetoprotein, vitamin D-binding protein and afamin.

The 3D structure of human serum albumin has been determined by X-ray crystallography to a resolution of 2.5 Å. Albumin is a 65-70 kDa protein.