The extension bunk (10) is intended for subsequent installation in the rear part (12) of a minibus or of an estate car with closeable rear opening (14). In the inserted position, it is completely accommodated in the vehicle whilst, in the extended position, it protrudes rearwards out of the vehicle for the greater part. On the side edges of the bunk floor (16), forwardly open running pipes (24) which are aligned parallel to the longitudinal axis of the vehicle are arranged. Furthermore, at lateral fixing points of the vehicle frame, a transverse member (26) is attached at the level of the running pipes (24), to which member (26) two freely rearwardly protruding vertical shafts (28) are attached, which shafts (28) engage in the running pipes (24) forming a telescopic guide. Within the bunk (10), four panels (44, 48, 52, 60) which are connected to one another at hinges and covered with padding are arranged, the front panel (44) of which can be detachably attached by its front edge to the transverse member (26) whilst the rear panel (60) is screwed to the bunk floor. In the inserted position, the two central panels (48, 52) are positioned obliquely so that a rear seat with backrest and a rear storage space (64) are formed. When pulling out the bunk, the two panels (48, 52) are folded downwards into a position in which they are flush with the first and fourth panels (44, 60) and form together with the latter an enclosed surface for lying on.