The low frequency (1/f) noise in single SnO2 nanowire transistors was investigated to access semiconductor-dielectric interface quality. The amplitude of the current noise spectrum (S-I) is found to be proportional to I-d(2) in the transistor operating regime. The extracted Hooge's constants (alpha(H)) are 4.5x10(-2) at V-ds=0.1 V and 5.1x10(-2) at V-ds=1 V, which are in general agreement with our prior studies of nanowire/nanotube transistors characterized in ambient conditions. Furthermore, the effects of interface states and contacts on the noise are also discussed.