The molecular mechanisms underlying prostate cancer metastasis remain poorly understood. The tetraspanin family member CD151 has been reported as an 'adaptor' between integrins and signal pathways. The role of CD151 in prostate cancer metastasis in vitro was investigated in this study. LNCap cells were transfected with wild-type CD151 cDNA, mutated CD151 cDNA and vector cDNA. The mutant (QRD ¹⁹⁴⁻¹⁹⁶ to INF) CD151 cDNA was created using QuickChange 2 site directed Mutagenesis kit (Stratagene). siRNAs were also used to knock down the CD151 expression in the prostate cancer cell line PC3. Proliferation, migration and invasion properties were measured after gene transfection and gene knock-down. There was no difference in proliferation of untransfected or control transfected LNCap cells vs. CD151 transfected LNCap cells (P>0.05). There was greater motility of CD151-transfected vs. control cells, when transferring through migration chambers with or without matrigel-coated membranes (P<0.01, P<0.01). Fewer numbers of mutant-transfected cells were found on the membranes for both migration and invasion studies (P<0.01, P<0.01). CD151 knock-down PC3 cells showed decreased motility (P<0.01), but no change in proliferation (P>0.05). Our data show that CD151 does not change the proliferative properties of prostate cancer cells, but does promote migration and invasion, and suggest that CD151 plays a specific role in promoting prostate cancer cell motility.