This thesis examines the concept of professional negligence. In doing so, it aims to find the distinguishing factors that characterize professional negligence as against other types of negligence. It seeks to emphasize the functions, duties and activities of professional people, rather than any examination of their status. The thesis demonstrates that this concept is based on a "broadspectrum" duty of care with specific obligations, particular to professional conduct. Consequently, this thesis argues whether society is looking at some change to the presumed responsibilities of a particular socio-economic grouping in Ireland or whether the law of tort merely seeks to accommodate technical and other changes by imposing liability in different ways. The thesis is arranged into three parts. In Part A, the thesis examines the existing literature on professional negligence to provide the context and background against which it explores the characteristics of professional negligence. It also justifies, in Chapter Three, what is meant by "professions". It examines the nature and function of professions and emphasizes, in particular, their autonomous nature, and the demand of professional judgment. In Part B the thesis examines the standard of care. Chapter Four examines the tests as used in Ireland and England Chapters Five and Six review the paramount Irish and English cases dealing with the alleged negligence of, m particular, medical practitioners and solicitors The objective of Part B is the description of a model or concept of professional negligence in Ireland. Part C examines, in Chapter Eight, the nature of the professional relationships underlying the interaction between clinicians and their patients, solicitors and their clients, and auditors and their companies for which they fulfil the requisite statutory and other functions. It also examines, m Chapter Nine, the imposition of a duty of care towards third parties. This involves a discussion of the development of negligence generally. Finally, in Chapter Ten, the thesis examines recent implications with regard to professional responsibility and professional discretion in Ireland.