The role of RNA polymerase (Pol) III in eukaryotic transcription is commonly 
thought of as being restricted to a small set of highly expressed, housekeeping 
non-protein-coding (nc)RNA genes. Recent studies, however, have remarkably 
expanded the set of known Pol III-synthesized ncRNAs, suggesting that 
gene-specific Pol III regulation is more common than previously appreciated. 
Newly identified Pol III transcripts include small nucleolar RNAs, microRNAs, 
short interspersed nuclear element-encoded or tRNA-derived RNAs and novel 
classes of ncRNA that can display significant sequence complementarity to 
protein-coding genes and might thus regulate their expression. The extent of the 
Pol III transcriptome, the complexity of its regulation and its influence on 
cell physiology, development and disease are emerging as new areas for future 
research.