The differential competitive ability of six winter lentil (Lens culinaris Medik.) cultivars and the traits that may confer such attributes was investigated in the presence or absence of weeds in a naturally occurring weed flora during 1997-1999 in Van, Turkey. For this purpose, six different winter lentil cultivars were used. The differences among the cultivars were not significant for weed densities and general coverage areas in 1998 and 1999. Weedy plots showed significant losses of yield depending on the cultivars, compared with weed-free plots. The lowest yield loss due to weeds were found in the varieties Yesil 21, Pul 11 and Sazak 91 in the first year; Kirmizi 5 1, Pul 11 and Kayi 91 in the second year of trials. These results suggest that the variety Pul 11 was the most competitive cultivar whereas Yerli Kirmizi was the least competitive. However, none of the varieties were really effective as a 'stand-alone' component for weed control in lentils. (c) 2004 Elsevier Ltd. All rights reserved.