Milligram per cent is a unit of measure in blood work: for any specified chemical, the mg% indicates the number of milligrams of that chemical in 100 milliliters of blood.
For example, a blood alcohol content of 100 mg% means 100 milligrams of ethyl alcohol per 100 milliliters of blood.
The redundant (and therefore potentially confusing) notation 'mg%/ml' is also used.[1]