Injection molding is one of the most extended plastic processing technologies, and is widely used with thermoplastic elastomers and rubber. Delivery of polymer melts into the mold cavity is the most important stage of the injection molding process. In the mold cavity the melt freezes on cures and the product gains the final shape and form. This paper shows the influence of cavity surface roughness and technological parameters on the flow length into mold cavity. The fluidity of polymers is affected by many parameters (mold design, melt temperature, injection rate and pressures) and by the flow properties of polymers. Evaluation of the data obtained by experiments where the testing conditions were widely changed shows that quality of the cavity surface does not affect the length of flow. Thermoplastics, TPEs and rubbers have been tested.