Despite general agreement that equity is part of the objective of the UK National Health Service (as indeed it is in other health services), there is little consensus on what is meant by equity in health care. This paper suggests seven possible definitions of equity not with the intention of trying to decide which is in any sense best but rather simply to try to reduce some of the confusion surrounding the concept of equity. These definitions include equality of expenditure per capita; equality of inputs per capita; equality of input for equal need; equality of access for equal need; equality of utilisation for equal need; equality of marginal met need; and equality of health. The paper then takes a closer look at some of the issues surrounding these definitions. The difference between equity by access and by utilisation lies in separating supply and demand (or need) issues. Thus equality of access is about equal opportunity: the question of whether or not the opportunity is exercised is not relevant to equity defined in terms of access. Utilisation is a function of both supply and demand. If access, a supply side phenomenon, is equalised, unless demand is the same, utilisation will not be equalised.(ABSTRACT TRUNCATED AT 250 WORDS)