Abstract: A parallel-slide gate valve with a sealing liner in two parts, comprises a semicircular lower housing part which can also be used as a mounting segment (30), and an upper housing part (31). The sealing liner (5) is also in two parts, wherein a transverse seal (20) which is subsequently compressible in operation is insertable in the liner stem (6). The assembly and dismantling of the parallel-slide gate valve can thus be effected in the direction of movement of the slide gate, and considerably ease the installation in relation to liner replacement. The mounting segment (30) can remain bolted to the pipe flanges when replacing the sealing liner (5), to align the pipe ends. The assembly is simplified in every respect, and all operating functions are optimally ensured.