The inhibition of tyrosine kinases involved in growth factor signal transduction pathways represents an attractive strategy for controlling aberrant cellular growth. Over the last 4-5 years, there have been numerous reports on the discovery of small molecule inhibitors for potential therapeutic applications to a number of proliferative diseases, principally cancer and restenosis, where the over-expression of certain tyrosine kinases has been demonstrated. These include, amongst others, the platelet-derived growth factor receptor, the fibroblast growth factor receptor, and the nonreceptor c-Src tyrosine kinase. This review compiles published reports and patent filings from 1995 to mid-1997 that include data directly related to inhibition of the platelet-derived growth factor receptor, fibroblast growth factor receptor, and Src family tyrosine kinases. Potential clinical applications for selected classes of tyrosine kinase inhibitors reviewed herein will likely depend on the demonstration of meaningful activity in a variety of therapeutic targets in animal models.