Please cite this article as: Y. Lee, H. Liu, Threshold for shock formation in the hyperbolic Keller-Segel mo del, Appl. Math. Lett. (2015), http://dx.Abstract. We identify a sub-threshold for finite time shock formation in solutions to the one-dimensional hyperbolic Keller-Segel model. The main result states that under some assumptions on the initial potential, if the slope of the initial density is above a threshold at even one location, the solution must become discontinuous in finite time.