We report a significant number of miRNAs and other non-coding small RNAs show dramatic changes in expression during development in C. elegans. RNAs were prepared from different time points during development of C. elegans hermaphrodites and males, and used for making cDNA libraries for small RNAs. Each library was sequenced using recent advances in high-throughput sequencing technology, Solexa. This study should lead to a better understanding of the aging process and age-related diseases.