Monocyte surface markers were identified by monoclonal antibodies. These molecules appear to be involved in cell adhesion reactions, antigen presentation, and different receptor functions. Some of them are non-lineage restricted, whereas other seem to be activation markers. On the other hand well known surface proteins exist, which are not involved in the CD designation (CD-cluster of differentiation) characterized by monoclonal antibodies. This paper is a short up-to-date overview of monocyte surface proteins.