The far-infrared spectrum of 1,4-disilacyclohexa-2,5-diene shows a series of four closely spaced bands originating at 70.5 cm(-1) resulting from the ring-puckering vibration. Four mid-infrared bands near 2214 cm(-1) result from combinations of the puckering with the Raman active B-2g SiH2 antisymmetric stretch at 2143.2 cm(-1), and seven difference bands near 2083 cm(-1) result from combinations with the Raman active A(g) SiH2 symmetric stretch at 2154.0 cm(-1). The ring-puckering transitions result from a single-minimum potential energy function, V(cm(-1)) = 1.23 x 10(4)x(2) + 2.40 x 10(4)x,(4) where x is the puckering coordinate. The molecule is planar and less rigid than 1,4-cyclohexadiene, thus apparently showing no unusual interactions between the silicon atoms and the C=C pi systems.