A treatment unit for surface treatment, in particular for painting, of articles, in particular of vehicle body parts, having a) at least one treatment chamber; b) a conveying system by means of which articles to be treated can be conveyed into the treatment chamber, through the treatment chamber along a conveying path (70, 72, 74, 76, 102, 104), and out of the treatment chamber again, wherein a direction of conveying that is tangential to the conveying path (70, 72, 74, 76, 102, 104) can be determined by each article at any position on the conveying path (70, 72, 74, 76, 102, 104); c) an application system which comprises at least one multiple-axis application robot (44, 46) which carries along an application means and can be moved along a robot movement path (60, 62, 88, 90). characterized in that d) the conveying system and the application system are arranged in such a way that the at least one application robot (44, 46) can be moved in relation to the direction of conveying of an article, optionally with da) a movement component parallel to the direction of conveying of the article and/or db) a movement component perpendicular to the direction of conveying of the article; e) the conveying system comprises a conveying rail system on which workpiece holders holding the articles to be treated can be moved; f) the conveying rail system comprises a track switch unit by means of which portions (64a, 64b, 66a, 66b) of the conveying rail system that run in the same direction or at an angle to one another can be connected to one another, such that different conveying paths (70, 72, 74, 76, 102, 104) for the articles can be determined optionally. a) at least one treatment chamber; b) a conveying system by means of which articles to be treated can be conveyed into the treatment chamber, through the treatment chamber along a conveying path (70, 72, 74, 76, 102, 104), and out of the treatment chamber again, wherein a direction of conveying that is tangential to the conveying path (70, 72, 74, 76, 102, 104) can be determined by each article at any position on the conveying path (70, 72, 74, 76, 102, 104); c) an application system which comprises at least one multiple-axis application robot (44, 46) which carries along an application means and can be moved along a robot movement path (60, 62, 88, 90). d) the conveying system and the application system are arranged in such a way that the at least one application robot (44, 46) can be moved in relation to the direction of conveying of an article, optionally with da) a movement component parallel to the direction of conveying of the article and/or db) a movement component perpendicular to the direction of conveying of the article; da) a movement component parallel to the direction of conveying of the article and/or db) a movement component perpendicular to the direction of conveying of the article; e) the conveying system comprises a conveying rail system on which workpiece holders holding the articles to be treated can be moved; f) the conveying rail system comprises a track switch unit by means of which portions (64a, 64b, 66a, 66b) of the conveying rail system that run in the same direction or at an angle to one another can be connected to one another, such that different conveying paths (70, 72, 74, 76, 102, 104) for the articles can be determined optionally.