We present here an easy-to-use computer program which finds oligonucleotides suitable as primers in polymerase chain reactions (PCR) or as probes for hybridization. In contrast to other programs used for this purpose, the additional advantage of this one is the possibility of directly detecting gene- as well as gene family-specific oligonucleotides. For this purpose, up to 200 different DNA sequences, of maximally 65,000 nucleotides each, can be scanned in a single search to ensure either single or multiple gene binding of the PCR primers or probes. Specific oligonucleotides for genes carrying internal repetitions and for single genes belonging to a set of highly conserved genes can also be detected. Many parameters such as exclusion of simple sequences, which are known to be highly repeated throughout various genomes or regions of stable secondary structures in both primer-primer and primer-template, can be taken into consideration and avoided. Furthermore, the G + C content and the length of the oligonucleotides can be changed in a broad range by the user.