An investigation of the product life cycle concept as an instrument in marketing decision-making for selected small organisations in South Africa. The product life cycle concept is currently a dominant component of marketing theory. There is however much criticism on and doubt about the applicability of the product life cycle concept as a marketing decision-making instrument. No evidence exists of the efficacy of the product life cycle concept as an instrument to develop marketing strategy. The purpose of the study was to test the underlying theory of the product life cycle concept with the primary objective of establishing what the use and practical value of the product life cycle concept is in making marketing decisions in small manufacturing and dealer organisations. The main focus was to test the ability of marketing decision-makers in small manufacturing and dealer organisations to associate their application and use of the product life cycle concept with Kotler's assumptions on the identified marketing characteristics, described marketing objectives and proposed marketing strategies. A major finding was that small organisations tended to display a marketing knowledge level that was not in total unison with the existing marketing theory. Another important conclusion of the study was that the current product life cycle concept theory needs to be broadened to include strategies on the expanded marketing mix (people, processes and physical evidence). Apart from the different use and application by marketing decision-makers in small organisations in South Africa the product life cycle concept theory has potential as a strategic tool and a high likelihood for its future use as a marketing decision-making instrument.