Despite the remarkable development due to the renovation policy initiated in 1986, Vietnam's rice sector is still facing the problem of raising the productivity for the necessity to increase the production on condition that the diversion from rice into the other crops is promoted. Such a productivity growth as in the past, however, might not be expected to realize in the future without improving the technical efficiency of farmers. This paper attempted to estimate the technical efficiency among rice farmers and inferred the numerical contribution to the enhancement of productivity and income, using farm level data collected in Red River Delta and Mekong Delta. For that purpose, we applied the frontier production function approach and used Seemingly Unrelated Regression for estimation of the function. We found that the varience of technical efficiency among farmers was the larger in Mekong Delta than in Red River Delta, because of the faster technical progress. We also found that the rice farmers could enhance the productivity by nearly one ton per ha and raise the income if they could improve their technical efficiency.