Summary: The basic reproduction number \(R_0\) serves as a threshold parameter of many epidemic models for disease extinction or spread. The purpose of this paper is to investigate \(R_0\) for spatial reaction-diffusion partial differential equation epidemic models. We define \(R_0\) as the spectral radius of a product of a local basic reproduction number \(R\) and strongly positive compact linear operators with spectral radii one. This definition of \(R\), viewed as a multiplication operator, is motivated by the definition of basic reproduction numbers for ordinary differential equation epidemic models. We investigate the relation of \(R_0\) and \(R\).