Process for producing pure methanol from a synthesis gas containing hydrogen and carbon oxides as synthesis gas constituents, comprising the steps of: (a) at least partially converting the synthesis gas containing hydrogen and carbon oxides under methanol synthesis conditions in a methanol synthesis unit containing at least one methanol synthesis reactor, (b) discharging a liquid crude methanol stream containing methanol, water, dissolved synthesis gas constituents and low-boiling byproducts from the methanol synthesis unit, (c) introducing the liquid crude methanol stream into a decompression vessel, discharging a liquid, decompressed crude methanol stream depleted in synthesis gas constituents as the bottoms product and a gaseous tops product stream comprising synthesis gas constituents from the decompression vessel, (d) introducing the liquid, decompressed crude methanol stream depleted in synthesis gas constituents to a prerun column, distillatively resolving said stream, discharging a liquid, stabilized, methanol stream depleted in low-boiling byproducts as the bottoms product stream and a gaseous tops product stream comprising low-boiling byproducts and methanol vapour from the prerun column, (e) introducing the bottoms product stream from the prerun column to a single- or multi-stage methanol purification apparatus, discharging a pure methanol product stream from the methanol purification apparatus, (f) sending the tops product stream from the prerun column to an offgas disposal apparatus, characterized in that (g) before sending to the offgas disposal apparatus, the tops product stream from the prerun column is subjected to a scrubbing step with a methanol-selective scrubbing medium in a scrubbing apparatus and a methanol-depleted tops product stream is sent to the offgas disposal apparatus, wherein water is used as the scrubbing medium and wherein methanol-laden water is discharged from the scrubbing apparatus and introduced to the methanol purification apparatus. (a) at least partially converting the synthesis gas containing hydrogen and carbon oxides under methanol synthesis conditions in a methanol synthesis unit containing at least one methanol synthesis reactor, (b) discharging a liquid crude methanol stream containing methanol, water, dissolved synthesis gas constituents and low-boiling byproducts from the methanol synthesis unit, (c) introducing the liquid crude methanol stream into a decompression vessel, discharging a liquid, decompressed crude methanol stream depleted in synthesis gas constituents as the bottoms product and a gaseous tops product stream comprising synthesis gas constituents from the decompression vessel, (d) introducing the liquid, decompressed crude methanol stream depleted in synthesis gas constituents to a prerun column, distillatively resolving said stream, discharging a liquid, stabilized, methanol stream depleted in low-boiling byproducts as the bottoms product stream and a gaseous tops product stream comprising low-boiling byproducts and methanol vapour from the prerun column, (e) introducing the bottoms product stream from the prerun column to a single- or multi-stage methanol purification apparatus, discharging a pure methanol product stream from the methanol purification apparatus, (f) sending the tops product stream from the prerun column to an offgas disposal apparatus,