A dynamic method for testing of biomaterials in vitro is designed and verified. This method is based on interaction of the material with a flowing solution, which simulates the composition of the inorganic part of human blood plasma. In experiments, bioactive chemically treated titanium (Ti-bio), TiO₂ gel, sintered hydroxyapatite (HA1100) and dried hydroxyapatite (HA120) granules were used. Titanium (grade 3) and silica glass granules were used as reference bioinert materials. With bioactive materials the test confirmed adsorption of Ca²⁺ and PO₄^3- ions in the initial phase of interaction and, after induction time (for Ti-bio 24.5 h, HA1100 2.5 h, HA120 3.8 h), the constant growth of bioactive layer of hydroxyapatite. During exposure of bioinert samples no changes in the effluent concentration were detected. The dynamic arrangement also enables a simple evaluation of precipitation parameters (induction time, growth rate), which can be used for bioactivity quantification of investigated materials.