It is evident that through effective creation and transfer of knowledge, organization would be able to gain competitive advantage and superior performance (Shiva et al, 2011). Knowledge sharing (KS), or flow, is the cornerstone of knowledge management (Szulanski, 1996; Gupta & Govindarajan, 2000) and thus, modern organizations are striving towards managing their knowledge so as to enable it to be shared effectively within the organization (Issa & Haddad, 2008). This is due to the fact that knowledge is now regarded as an asset capable of giving many untold benefits that make a difference between successful and less successful organization (Collins & Hitt, 2006). Researchers have argued that individuals, namely knowledge workers, are the prime source of knowledge (Jarvenpaa and Staples, 2001), and are important for the creation, capture and sharing of knowledge within organizations (Abdusttar, 2005; Von Krogh et al, 2000). However, most people in most organizations do not have the ability to act on the knowledge they possess (Abdusttar, 2005). More importantly, research indicates that employees in most organizations refuse to share knowledge among each other (Shiva et al, 2011). Others argued that most knowledge management systems suffer from the problem of low degree of participation either in KS. Therefore, this study aims to investigate factors that affect KS in Jordanian pharmaceutical companies. Using questionnaire survey of 13 pharmaceutical companies in Jordan this study examined factors that affect KS in these companies. The study found that higher levels of learning orientation results in higher levels of KS. The study also found that the existence of an effective communication system results in higher levels of KS.