Observer synthesis for linear positive systems is treated. The concept of observability of a linear positive system is defined and a characterization of observability is provided. An observable canonical form is proposed for a linear positive system with respect to an equivalent relation defined by permutations of the state and of the output set. Observer synthesis is carried out for linear observers which are either globally asymptotically stable or whose error dynamics is assignable. An algorithm for the construction of a linear observer is stated which is based on the observable canonical form. © 2007 Elsevier Inc. All rights reserved.