A specialty specific ontology for dermatology can be a very useful tool for conveying an accurate meaning to collaborative guideline applications and software systems. This paper describes the basics of ontology and the need for ontology in dermatology. We also propose the basic structure for one such ontology called ONTODerm. ONTODerm is grounded on DOLCE Lite foundational ontology and its purpose is to address the unique needs of dermatology as a medical specialty. It is represented in Web Ontology Language (OWL) using the Protégé OWL Plugin. ONTODerm is available for download and collaborative development under GPL license.