We discarded all the error prone clusters in UniGene that contain only one sequence. Having the number of the remaining UniGene clusters multiplied by possible average number of alternative splicing, we could match the two databases. For example, the number of human UniGene clusters after the treatment is 82,718. After multiplied by the possible number of alternative splicing 4, we got 330,872, which is close to the result of TGI. The UniGene result of mouse is 56,365 4 = 225,460, which is close to TGI result 210,249. We supposed the average number of alternative splicing for mammals is 4, for birds is 3, for fishes, amphibians and chordates is 2, for other animals is 1.5, for plants is 2~2.5, to make the results from the two databases as consistent as possible. We also referred to other databases.