Whena family of genes from closely related organisms is known,there is a certain chance to extract the corresponding gene from the genomeof another related organism. This can be done by polymerase chain reaction, providedthat a pair of suitable primers can be designed. In contrast to primer design for a single, knowntarget sequence, systematic primer design for an unknowntarget given a group of homologues can by no meansbe done manually. GcneFisher is a software tool which automates this task, and takes special care to makethe impact of the manifold design parameters transparent to the user.