Although wide variations exist among service professions, several common attributes affect the role of advertising in the service industries. For example, because a service is intangible, it cannot be evaluated before purchased or consumed. Depending on the degree of intangibility, the consumer's assessment becomes that much more difficult, and the role of advertising becomes increasingly important. Other common attributes of service professions include the variable length of the purchase cycle, products that are non-standardized and personalized, service perishability, and consumer participation in the service exchange. A case study of health care advertising illustrates the necessity and effectiveness of advertising in a service profession. Multiplying health care options, changes in consumer perceptions, and ethical issues are all forcing hospitals to become more responsive to consumer demand, and to embrace the principles of marketing. Consumers are making major decisions and searching for ways to distinguish alternatives. Advertising, by providing information about service marketing, serves a useful function for the consuming public. (Two appendixes listing guidelines for hospital advertising and the Council of Medical Speciality Societies' advertising guidelines, and 54 endnotes are appended.) (MM)