Most of the Scandinavian members of the orchid genus Dactylorhiza are included in the D. incarnata/D. maculata polyploid complex. Molecular data obtained during the last decade have given a better understanding of evolutionary patterns in this complex and explain why it is taxonomically difficult. The data reveal that allotetraploids have been formed repeatedly by hybridization between the same pair of broadly defined parental species, D. incarnata s.lat. and D. maculata s.lat. Some of the widespread allotetraploids are themselves variable and may each consist of several independently derived allotetraploid lineages, or else may have obtained increased levels of diversity by backcrossing with their parental species or by hybridization with other allotetraploids. Whereas some allotetraploids have wide distribution areas indicating that they should be of relatively high age, other allotetraploids, which may be characterized by odd character combinations, are confined to one or a few populations and may be of recent origins. Because of the intricate variation patterns and the difficulty to subdivide the complex into a series of morphologically discrete species, it is argued that all allotetraploids are best included in a broadly circumscribed D. majalis, at least until additional molecular data regarding taxonomic delimitation have been obtained. Widespread and well-known taxa may be provisionally treated as subspecies.