A farm survey was carried out in 1992 among 138 individual farm households located in seven provinces in Thailand to provide a detailed input-output characterization of mung bean (Vigna radiata (L.) Wilczek] growing in Thailand, to analyse its profitability, to investigate the major constraints, and to assess the adoption of modem mung bean varieties. The survey data were analysed for dry season lowland and wet season upland mung bean growers, separately and as a whole. The results indicated that, despite large differences between individual growers, the average net income per unit area of mung bean was at least as high as that of alternative crops. However, returns to labour earned from mung bean substantially exceeded those from other crops. Wet season mung bean cultivation tended to be considerably more profitable than dry season mung bean production, mainly due to higher yields. Adoption of modem mung bean varieties has been rapid with currently over 90% of the total mung bean area under varieties developed with parent material from the Asian Vegetable Research and Development Center. Podborer infestation was by far the most serious factor reducing yield in mung bean in Thailand. Drought stress in the lowlands was the second most important. The supportive role of government policies in increasing the adoption of improved mung bean technologies, as well as the importance of close collaboration among farmers, extension services, researchers, and traders are highlighted. Several suggestions are offered for further improvements in mung bean productivity in Thailand.