Primary cilia are sensors of chemical and mechanical signals in the extracellular environment. The formation of primary cilia (i.e. ciliogenesis) requires dynamic membrane trafficking events, and several Rab small GTPases, key regulators of membrane trafficking, have recently been reported to participate in ciliogenesis. However, the precise mechanisms of Rab-mediated membrane trafficking during ciliogenesis remain largely unknown. In the present study, we used a collection of siRNAs against 62 human Rabs to perform a comprehensive knockdown screening for Rabs that regulate serum starvation-induced ciliogenesis in human telomerase reverse transcriptase retinal pigment epithelium 1 (hTERT-RPE1) cells and succeeded in identifying Rab34 as an essential Rab.