Mixing device for a gas burner

A mixing device (10) for a gas burner, with a housing (11) having a combustion air inlet (13), a gas inlet (14) and an outlet (15) for the mixture of gas and combustion air, and with a Venturi device (12) which is positioned in the housing, wherein the Venturi device is contoured to form a contraction section (19), a mixing section (20) and a diffuser section (21). A guide device (22) for combustion air, which divides combustion air which enters the mixing device via the combustion air inlet (13) into a primary flow and a secondary flow, may be positioned inside the Venturi device, wherein the combustion air of the primary flow, issuing from the combustion air inlet, can be fed to the mixing section (20) via the contraction section (19), and wherein the combustion air of the secondary flow, issuing from the combustion air inlet, can be mixed downstream of the mixing section (20) in the region of the diffuser section (21) with the mixture of the gas and the combustion air of the primary flow.