Brittle polysilicon rods having a rod cross-section of 80-99% available for electrical conduction and a flexural strength of 0.1 to 80 N/mm2 are produced by a process wherein the temperature of the bridge of polysilicon rods in the Siemens process is held at a high temperature and the flow rate of chlorosilanes is increased to the maximum within a short time. The rods are easily fragmented with low force, resulting in polysilicon with a low level of metallic impurities.