This paper contains estimates of comparative labour productivity levels in manufacturing for the Soviet Union and the USA. Value added was converted to a common currency by using an expenditure based unit value ratio (or purchasing power parity). Time series for value added and labour inputs were used to estimate relative Soviet/US productivity levels back to 1928. The main findings are that in 1987, Soviet value added per person employed was 24.8 per cent of American levels. Value added per hour was 26.3 per cent of the USA. Combining US and Soviet time series for output and employment together with the results of the detailed comparison of labour productivity for 1987, brought me to the conclusion that over the period 1928-89 Soviet labour productivity inproved very little relative to the US. The results of this study are partly based on Soviet datasets that were formerly not available to researchers