A research report Submitted in Partial/Fulfillment of the Requirements for Award of the Degree of Master of Business Administration (MBA) of Mzumbe UniversityThis study assessed the contribution of advertising on sales improvement with case study of Zanzibar Bottlers Limited. By using descriptive case study a representative sample of 70 respondents was obtained from the population of 435. The methods of data collection involved both primary and secondary sources. Primary data were collected by using questionnaire, interview guide, documentary sources, and observation. Whereas documentary review was used in secondary method. The Statistical Package for Social Sciences (SPSS) software, MS excel and simple calculations by calculator were used to analyze the data where simple frequencies and percentages were created. The findings revealed that advertising contribute much on sales improvement where by 88 percent of the respondents said informative advertising affect sales of ZBL, 80 percent said remaindering advertising affect sales improvement and 64 percent have replied that persuasive advertising affect sales improvement. The researcher therefore calls for the administration of ZBL to pay attention on advertising strategies for the sake of embracing market share, goodwill, profitability as well as sales of the company.