European experiments on Miscanthus have so far been concentrated on one genotype, namely the triploid, infertile hybrid M. ''Giganteus''. Chemical analysis of this genotype has shown relatively high mineral contents which reduce its quality for power production. This paper presents the yields and concentrations df N, K and Cl in 15 selections of the species M. sinensis, and compares these to data on M. ''Giganteus''. Yields were rather low during the experimental period 1992-1995 due to adverse climatic conditions. Average dry matter yield over three years of measurements at spring harvest was 8.9 t/ha for M. sinensis selections and 7.7 t/ha for M. ''Giganteus''. The percentage content of N, K and Cl in plant dry matter as a mean of three years was 0.64, 0.39 and 0.08 in the M. sinensis selections and 0.59, 0.81 and 0.33 in M. ''Giganteus''. There were large variations in yield and mineral concentrations within the selections of M. sinensis, and some of the selections seem to meet the target fuel specification values for K and Cl content set by the Danish Power Pools. During 1994/1995, plant material was sampled almost monthly from M. ''Giganteus'' and from two selections of M. sinensis. Mineral concentrations were of the same order of magnitude in the three genotypes during most of the growing season. However, during the winter, the K and Cl content decreased more in M. sinensis than in M. ''Giganteus''. In the Danish climate only M. sinensis flowers and shows physiological senescence, while M. ''Giganteus'' stays in the vegetative stage until it is killed by the frost. This is probably part of the reason for the difference between genotypes in K and Cl lability, but the possible influence of other factors is also discussed. The genotypical variation found in Miscanthus can be used in a breeding programme to create genotypes to match different climatic conditions and to produce biomass of specific qualities. (C) 1997 Published by Elsevier Science Ltd.