Knowledge is now recognized as a company's most valuable asset. For the most part it resides in employees as tacit knowledge. Owing to the nature of tacit knowledge, efforts to diffuse it into an organization come with distinct challenges. The research objective was to identify the challenges of tacit knowledge diffusion that were most relevant and important to Eli Lilly SA, rank them in order of importance and make recommendations thereof. From the literature survey, nine hypotheses were developed and tested through a questionnaire sent via e-mail to 154 employees at Eli Lilly SA. Eighty-one responses were received of which 80 were used for analysis (53% response rate). Of the nine hypotheses, four were rejected while five were accepted. The main challenges identified that Eli Lilly SA faced when diffusing knowledge were distance and time. The conclusion was that Eli Lilly SA needed to build on the area of strength identified, which was leadership, and address the major challenges of distance and time by optimizing existing systems that were already in place in the organization.