In a turbine for an exhaust gas turbocharger of an internal combustion engine having a housing part with accommodation space including a turbine wheel and at least one spiral channel via which exhaust gas of the internal combustion engine may flow. The spiral channel has an outlet cross-section via which the turbine wheel accommodated in the accommodation space may be acted on by the exhaust gas, and has at least one blocking member, which is connected to an adjusting part so as to be movable hereby in the peripheral direction of the accommodation space for adjusting the outlet cross-section (AR, ARλ, AR,RGR). A bypass duct is provided, via which exhaust gas can bypass the turbine wheel and whose flow cross-section is also adjustable by the blocking member moved the adjusting part.