Genome projects require a high-throughput method for DNA template preparation, which traditional protocols can rarely provide. We introduce here a new protocol for plasmid and cosmid DNA preparation based on alkaline denaturation in a 96-well format. The essential improvement made in this protocol on previous 96-well preparation includes the purification by Pro-Cipitate in 96-well microfilters. The yield and quality of DNA are sufficient for restriction digestion, radioactive sequencing, and automated fluorescent sequencing. It is also significantly more cost-effective than several of the commercial mini-prep kits.