In mammals, longitudinal bone growth results from the precise coupling of chondrogenesis and osteogenesis within the epiphyseal growth plate, a process termed endochondral ossification. The mechanisms coupling chondrogenesis and osteogenesis are unknown. Previous studies have shown that both basic fibroblast growth factor (bFGF) and acidic FGF are expressed by growth plate chondrocytes. Here we show that bFGF, infused directly into the rabbit proximal tibial growth plate, accelerates vascular invasion and ossification of growth plate cartilage. Our results suggest the possibility that bFGF (or a related member of the FGF family) couples osteogenesis to chondrogenesis by attracting vascular and bone cell invasion from the adjacent metaphyseal bone.