The purpose of this study is to determine the extent to which pharmaceutical and medical industries firms in Jordan adopt knowledge management practices (KMPs), and more importantly, to examine the relationship between KMPs and organizational performance (OP). Further, the study aims to determine the effect of firms' size and firms’ age on the relationship between the KMPs and OP. The study found a positive and significant relationship between KMPs and OP. More specifically, the result showed that KMPs have more strong and positive impact on new product success. The study also found that training and competence development have more strong and positive impact on OP. The study findings revealed that pharmaceutical and medical industries firms in Jordan adopt KMPs in a high but not strongly enough level. The study also found a significant variation in the impact of KMPs on OP in terms of firm age. In contrast, the study did not find significant variation in the impact of KMPs on OP in terms of firm size. Research provided new information not only in terms of filling the gap of the newness of KMPs in Jordan, but also it has implications on the relationships between KMPs and OP.