This work is devoted to the optimization of the trajectory of a robotic system for aliquoting biosamples, consisting of serial and parallel manipulators. Optimization consists of two stages. At the first stage, optimization constraints associated with the workspace, taking into account the ranges of permissible values ​​of the angles of the drive rotational joints, the link interference and singularities. The workspace in the space of input and output coordinates is represented as a partially ordered set of integers. At the second stage, restrictions are formed related to the objects that are in the workspace during the aliquoting process, such as the body of the robotic system, test tubes and racks. The condition for excluding collisions of the manipulator with other objects is provided by geometric decomposition of objects and exclusion of areas corresponding to external objects from the set describing the workspace of the manipulator. Optimization is performed in the space of input coordinates. The objective function is proportional to the duration of movement along the trajectory. The possibility of evolutionary algorithms application for solving this problem is analyzed. An assessment of their performance is given. Optimization and export of the resulting trajectory are implemented in software, which allows you to verify the optimization results on a virtual model. The simulation results are presented.