The paper estimated the technical efficiency index of Taiwan rice farmers using panel data and a stochastic production frontier with heteroscedasticity during the period 1998-2004. The empirical results show that there were trends of own-labor-saving, mechanization of operations, fertilizer-using, and farm size expansion by lease. A higher level in labor intensity, the ratio of mechanical labor, or the ratio of rented land would yield a higher technical efficiency. Labor and fertilizer were risk-decreasing inputs while land was the risk-increasing input. Moreover, production risk was affected by temperature but not by precipitation. Finally, according to the regression results, the technical efficiency during 2001-2004 was lower than that during 1998-2000 while the production risk of the former was higher than the latter.