A microfluidic mixing device comprises a main channel and a number of secondary channels extending from a portion of the main channel and entering another portion of the main channel. A number of actuators are located in the secondary channels to pump fluids through the secondary channels. A microfluidic mixing system comprises a microfluidic mixing device. The microfluidic mixing device comprises a main fluid mixing channel, a number of main channel actuators to pump fluid through the main fluid mixing channel, a number of secondary channels fluidly coupled to the main fluid mixing channel, and a number of secondary channel actuators to pump fluids through the secondary channels. The microfluidic mixing device also comprises a fluid source, and a control device to provide fluids from the fluid source to the microfluidic mixing device and activate the main channel actuators and secondary channel actuators.