Effects of impeller and baffle conditions on mixing time was discussed for baffled and non-baffled agitated vessels with paddle, pitched-blade paddle and turbine impellers. First, the effects of tracer injection position and baffle condition on mixing time were examined experimentally. At the baffle condition of n(b)(0.8)(Bw/D) greater than or equal to 0.1 the mixing time measured was almost uniform independently of the tracer injection position. Second, the effect of impeller conditions on mixing time was examined experimentally. The mixing time in a baffled agitated vessel with a paddle impeller was well correlated using the impeller condition parameter n(p)(0.7)(b/d), and a mixing time correlation was proposed. The mixing time in a baffled vessel with a pitched-blade paddle impeller was correlated in the same manner as for the paddle impeller, by modifying the impeller condition parameter as n(p)(0.7)(bsin(1.6)theta/d). For a small paddle impeller (d/Dless than or equal to0.3) and small pitched-blade paddle impeller (d/Dless than or equal to0.4), the mixing time in a non-baffled agitated vessel coincided with that in a baffled vessel.