OLIGO performs a range of functions for researches in PCR and related technologies such as PCR and sequencing primer selection, hybridization probe design, inverse and real-time PCR, analysis of false priming using a unique priming efficiency (PE) algorithm, design of consensus and multiplex, nested primers and degenerate primers, reverse translation, and restriction enzyme analysis and prediction; based on a protein sequence, oligonucleotide database allows fully automatic multiplexing, primer secondary structure analysis, and more. OLIGO allows for sequence file batch processing that is essential for automation. This chapter describes the major functions of OLIGO version 7 software.