Abstract: DNA ligase activity is strongly accelerated in the presence of high concentrations of non-specific polymers, with an accompanying change in product distribution characteristics. The rate of blunt-end ligation of DNA substrate by T4 DNA ligase is particularly affected, with a product shift from closed circular species to linear oligomers. The method provides a way to increase the rate of enzymatic DNA ligation and the size of the linear products. It may be useful when preparing large amounts of polymers by ligation of oligomers or when ligating amounts of DNA or deoxyribooligomers so low in concentration that a reduced yield would otherwise result.