MicroRNAs (miRNAs) are small, endogenous, non-coding RNA species, about 21 nucleotides in length, which modulate the expression of animal and plant target genes at the post-transcriptional level. It has been shown that miRNA based gene regulation plays a pivotal role in pathways involved in growth and development. Understanding miRNA mediated processes requires new technologies enabling efficient detection of small RNA species. Here we report the optimization of a miRNA Northern blot detection method based on LNA (locked nucleic acid)-modified oligonucleotide hybridization. This technique allows sensitive and highly specific detection of mature miRNAs.