Ribosomal protein L8 is a component of the 60S subunit of the ribosome and is involved in protein synthesis but its role in Drosophila development is not well understood. We depleted L8 through RNA interference (RNAi) to examine its effects on fly development both in vivo and in vitro. The results demonstrated that L8 RNAi caused embryonic or first-larval lethality, delay of larval development, defects in eye and wing morphology, and dramatically reduced the number of S2 cells. This indicated that L8 plays a crucial role in Drosophila development. Acridine orange staining of the wing discs showed that apoptosis occurred when L8 was depleted, indicating that depletion of L8 is tightly connected to apoptosis. RT-PCR analyses of the transcription level of genes that are known to be key factors in apoptosis (p53, hid, reaper, dark, Dcp-1) and cell cycle regulation (cdc45, MCM3, cyclin B, incenp) in L8-deficient S2 cells, were consistent with their role in apoptosis induction and cell cycle arrest. These results indicate that depletion of L8 strongly impairs Drosophila development, and that this depletion is associated with cell proliferation arrest and apoptosis, in which p53 may play a central role.