Identicells are made up of 10 vials which each contain either a 3% or 0.8% suspension of red cells derived from the blood of a single group O donor. The donor cells have been washed to remove blood group antibodies and then resuspended in a preservative solution containing adenine and inosine to help carbohydrate metabolism and chloramphenicol (0.34 mg/ml) and neomycin sulphate (0.10 mg/ml) as preservatives. Each cell has been selected to represent the most frequently inherited antigens. Less frequently inherited antigens are provided whenever possible.