The glutamate hypothesis of schizophrenia derived from evidence that phencyclidine, a noncompetitive N-methyl-D-aspartate (NMDA) antagonist, produces schizophrenia-like symptoms in healthy humans. Sensorimotor gating, measured by prepulse inhibition (PPI), is a fundamental form of information processing that is deficient in schizophrenia patients and rodents treated with NMDA antagonists. Hence, PPI is widely used to study the neurobiology of schizophrenia. As the use of PPI as a model of gating deficits in schizophrenia has become more widespread, it has become increasingly important to assess such deficits accurately. Here we identify a possible role of mGluR5 in PPI by using wild type (WT) and mGluR5 knockout (KO) mice of two different background strains, 129SvPasIco and C57BL/6. In both strains, PPI was disrupted dramatically in the mGluR5 KO mice throughout a range of interstimulus intervals and sensory modalities. The present findings further support the glutamate hypothesis of schizophrenia and identify a functional role for mGluR5 in sensorimotor gating.