Abstract: Objective To predict orthologous sequences of the GENCODE-identified 13 562 human long non-coding RNAs (lncRNA) in 16 mammalian genomes and construct a lncRNA database LongMan for lncRNA studies. Methods The exon structures of a total of 13 562 human lncRNAs were analyzed using RNAfold, and their orthologous sequences were searched against 16 mammalian genomes using Infernal. The potential orthologous genes, transposons and splicing signals of human lncRNAs were predicted to construct a lncRNA database with a updating mechanism. Results and Conclusion The lncRNA database LongMan we constructed, which currently contains 133 646 orthologous lncRNAs, provides information of the sequences, alignments, transposons, and species-specific insertions and deletions and allows database search on combinatorial conditions, graphic display and data download. As the first large-scale mammalian orthologous lncRNA database, LongMan has important values in future comparative and functional studies of lncRNAs.