In this paper we describe our work on representing and constructing ontologies for breast mammography, which is part of planned set of comprehensive breast imaging and pathology ontologies designed to support the screening and diagnosis of breast cancer. We select DAML+OIL as the web-enabled ontology modelling language because of available support for description logic-based reasoning. We also discuss experiences obtained from constructing such an ontology in the hope that they can be beneficial for work on similar domains.