UniGene at NCBI is a database of non-redundant set of gene-oriented clusters. Each UniGene cluster, represented by a uniqe UniGene identification number, contains sequences that represent a unique gene.

UniGene identification numbers have been used for identifying unique genes. Searching UniGene for sequences and gene information is sometimes more efficient since there is less redundant information.

However, it should be noted that the procedures for automated sequence clustering are still under development and the GenBank, based on which the UniGene databases are build, is ever expanding. As a result UniGene clusters many change from time to time. Users are suggested to note the build number when using UniGene databases.