Dear biomaRt developers, The following getBM function call returns 0 record of miRNAs for c.elegans. It works fine for human. FYI, the martview website does not display any miRNA for c.elegans either. Could you please help? Many thanks! library(biomaRt) mart=useMart(biomart="ensembl",dataset="celegans_gene_ensembl") miRNA = getBM(c("ensembl_gene_id", "chromosome_name", "start_position", "end_position", "strand", "description", "gene_biotype"), filter = c("biotype"), values = "miRNA", mart = mart) Best regards, Julie