A multifunctional control valve for gas measurement instruments, e.g., for respiratory gas analysis, is disclosed. In at least one embodiment, the multifunctional control valve includes a first inlet opening, an outlet opening, a main line, and a bypass line, wherein a measurement chamber is in the main line, wherein the measurement chamber is arranged downstream of a first multiway valve which can selectively connect the main line or the bypass line with the inlet opening, and wherein the measurement chamber is arranged upstream of a second multiway valve which can selectively connect the main line or the bypass line with the outlet opening.