Switchgrass has been proposed as a perennial plant suitable for biofuel production. Cultivar selection has a major impact on the ultimate productivity, persistence and profitability of the crop. The purpose of this work was to evaluate 16 switchgrass varieties (upland and lowland ones) for 5 years in Greece and Italy. One single winter harvest was carried out every year when the moisture content was less than 20% and biomass yields were determined. At the end of each growing season, the stem height and the number of tillers per square meter were measured. It was found that all varieties performed high yields in both sites except for the varieties 9005439 (upland) and 9005438 (lowland), which produced only 5.6 and 6.9 t ha(-1), respectively. All varieties produced their best yields in the third growing season, 17.9 t ha(-1) in Greece and 12.3 t ha(-1) in Italy. Significantly higher mean yields were recorded in the Greek trial, apart from the lowland variety SL 93-3 that produced 20.8 t ha(-1) in Italy and 18.1 t ha(-1) in Greece. The lowland varieties (Cathage, Kanlow, SL 93-2 and SL 93-3) were found to be more productive compared to the upland varieties, averaged over the sites and the years. The best performing variety on every site (mean 1999-2002) was a lowland variety, Kanlow (17.1 t ha(-1)) in Greece and SL 93-3 (20 t ha(-1)) in Italy. (c) 2008 Elsevier Ltd. All rights reserved.