Numerical simulations were performed to study fluid mixing in a novel two-dimensional in-line mixer utilizing multiple impinging stream inlets operated in the laminar flow regime. Effects of the inlet jet Reynolds number as well as mixer geometry on the mixing characteristics are investigated and discussed. Offsetting the top and bottom inlet jets is effective in improving the quality of mixing due to the presence of intense mixing zones between the inlet jets. It is found that the operating as well as geometric parameters affect mixing differently in different zones of the mixer. Results show that excellent fluid mixing is achievable over a rather short axial distance in this mixer.