Bovine serum albumin (BSA)-coated haemoglobin (Hb)-microcapsules prepared by co-precipitation of Hb and MnCO3 may present an alternative type of artificial blood substitute. Prepared microcapsules were analysed by Scanning electron microscopy (SEM) and Respirometry, cytotoxicity was evaluated by addition of microcapsules to murine fibroblast-derived cell line L929 (American Type Culture Collection, NCTC clone 929 of strain L). The capsules come along with a mean diameter of approximately 0.6 mu m and a mean volume of 1.13 x 10(-19) L, thus an average human red blood cell with a volume of 9 x 10(-14) L is about 800,000 times bigger. Hb-microcapsules are fully regenerable by ascorbic acid and maintain oxygen affinity because oxygen is able to pass the BSA wall of the capsules and thereby binding to the ferrous iron of the haemoglobin entity. Therefore, these microcapsules present a suitable type of potential artificial haemoglobin-based oxygen carrier (HbOC).