Method for paraffin isomerization

The invention relates to a process for isomerizing a feed essentially comprising hydrocarbons, preferably paraffins containing principally 4 to 8, preferably mainly of 4 to 6, even more preferably mostly 5 and / or 6 carbon atoms per molecule, comprising a fractionation zone and at least two reaction zones of isomerization, said method comprising the implementation of the following steps: (1) is sent to the load in a fractionation zone, (2) is removed at least part of the liquid circulating in said zone by at least two sampling levels (3) will direct most of the liquid collected in step (2) in at least two isomerization levels, each isomerization zone being associated with a draw-off level, (4) is sent to the bulk of step effluent (3) fractionation zone, substantially near levels abstractions ement, (5) recovering an effluent of the fractionation zone.