To be successful, businesses have to view their markets as consisting of distinct customer groups, each with their own distinct set of requirements and then deliver targeted offers to the customer groups they select to serve. Market segmentation is an essential prerequisite for commercial success. THe aim of this study was to evaluate the importance being attributed to market segmentation, targeting and positioning by the Top Hundred Companies of Mauritius. Questionnaires relating to market segmentation were adminstered to marketing managers of these companies. The findings were that most of the companies has a formal marketing planning system and marketing managers also believed that market segmentation is important. However, segmentation and product positioning were carried out informally. It was also found that the most commonly used segmentation variables were region, income, age, lifestyle and attitude towards the product. However, religion was not a very popular segmentation variable even though Mauritius is a multicultural country. Mauritian companies encountered numerous difficulties when trying to implement market segmentation.