The paper examines official Soviet estimates of the change in total output and output per worker in Soviet industry during World War II. These are shown to have understated wartime industrial performance by a significant margin. New estimates of industrial production, labour inputs and productivity are put forward. The likely contribution to maintenance of total output and labour productivity arising from the rapid structural change in favour of munitions work is also assessed. While output per hour worked in munitions branches of industry grew rapidly, the productivity of labour in civilian branches may have deteriorated before recovering to prewar levels in 1944.