A guide structure for a chain for an article conveyor is disclosed. The guide structure includes a guide for guiding the chain along a direction of movement of the chain and having at least two rails each delimiting a respective guide channel for at least partly accommodating the chain. An accompanying means for supporting the chain and accompanying it into the guide channel, wherein the accompanying means comprises a contact surface adapted to be in contact with the chain while the chain is accompanied into the guide channel. A fixing means for keeping the accompanying means in fixed position with respect to the guide. And, an adjusting means for adjusting a position of the accompanying means generally orthogonal to the direction of movement of the chain to adjust the angular position of the accompanying means with respect to the guide in at least a first and a second angular positions.