Energy use in the pre- and post-farm-gate sector of the food system is reported for crop production up to the retail outlet stage in Hong Kong in 1971. The overall energy balance is compared with a small section of the area devoted to intensive vegetable crop production, and also with an example of crop production in China in the mid 1930's. These points along a continuum show the increasing extrasomatic energy expenditure which has accompanied the implementation of western agricultural technology in the region. For crop production in a selected village in China in 1935–1937, the energy input— output ratio was 1 : 24.4, compared with 1 : 1.2 for all of the Hong Kong crop production in 1971. For high technology production in a portion of Hong Kong agriculture in the same year the energy input—output ratio was 1 : 0.13. The post-farm gate sector of the Hong Kong food system studied used as much energy to operate as the somatic energy contained in the food handled. It is estimated that 40–50% of the energy invested in the Hong Kong food system in 1971 could be conserved without a significant decline in crop production, although there is little economic incentive to achieve such energy conservation. These findings are discussed in the context of the expanding networks of dependency likely to be experienced by developing countries as energy flow in their food systems increases.