In the present study the expression patterns of ADAM (a disintegrin and metalloprotease) genes in the chicken developing lens were analyzed. Using in situ hybridization, we found that seven members of the ADAM family including ADAM9, ADAM10, ADAM12, ADAM13, ADAM17, ADAM22, and ADAM23 are expressed in the developing embryonic lens. From embryonic incubation day (E) 2 to E3, most of the ADAMs investigated here are expressed in the lens placode and lens vesicle. From E5 to E7, all seven ADAMs, but predominantly ADAM9 and ADAM10, are throughly expressed in the central epithelium, as well as in the proliferating lens epithelium and the equatorial lens epithelium. From E9 to E14, expression of ADAM9, ADAM10, and ADAM17 decreases moderately in these regions. ADAM12 and ADAM13 are weakly expressed in the central epithelium and the lens epithelium, and are not detectable from E14 onward. ADAM22 and ADAM23 are expressed in the central epithelium, the lens epithelium and the equatorial lens epithelium at E5 and decrease gradually afterwards in the same regions. At E16, only weak ADAM9, ADAM10 and ADAM17 signals are found in the anterior lens epithelium. The changing spatiotemporal expression of the seven ADAMs suggests a regulatory role for these molecules during chicken lens development.