This paper presents the results of a survey on about 350 households that reside in two hamlets in Hoa An village, Phung Hiep district, Can Tho province, in the Mekong Delta. The survey was carried out in 1993 and in 1997 to identify the changes in conditions of objective households. Generally speaking, an interval of four years might not be long enough to analyze structural changes. However, our analysis revealed the rapid development of the agricultural structure under the Doi Moi policy. Firstly, within four years, 46 households (13.5%) migrated from the surveyed area and 36 households (10.9%) migrated to the area, showing the high mobility of some households, especially in the case of small landowners and landless households. Secondly, the number of households in the medium-sized class (1.5-2.0 hectares) and total land area belonging to this class increased markedly. This class tended to adopt diversified farming systems as its technical basis of development and introduced mainly this technology into the surveyed area. Farmers' organizations contributed largely to this diversification through their activities like the introduction of new varieties, financing and dissemination of new technology.