Abstract: Antibodies having a high specificity and high affinity towards the human gene product MUC1, which in specific variants is associated with neoplastic cells, i.e. tumor tissue, to the use of the antibodies for medical purposes, i.e. for tumor treatment, and for analytical purposes, e.g. for tumor diagnosis. Compositions comprising the antibodies, e.g. for use in the analytical processes and analyses, to pharmaceutical compositions comprising the antibodies, and to use of the antibodies in the manufacture of pharmaceutical compositions for tumor treatment or for diagnostic purposes.