Fuelled by the drive to complete the Human Genome Project, many laboratories have developed new methods of screening clone libraries. From PCR-based strategies to pooling schemes and increased automation, the tedious task of library screening has become less labour-intensive and more cost-efficient. Currently, two main screening methods dominate: hybridization and polymerase chain reaction (PCR). In the following article, we present a brief overview of hybridization and PCR-based screening of yeast and bacterial libraries. Multi-faceted approaches combining different techniques, as well as less frequently employed methods such as fingerprinting are also described.