A major constraint of lentil (Lens culinaris Medik.) cultivation is yield reduction due to field infestation by the seed beetles Bruchus spp. (bruchids). The aim of the study was to assess seed loss (SL) and yield loss (YL) due to bruchid infestation under organic and conventional farming, and to investigate genotypic variability for seed yield of 20 lentil varieties in response to bruchid damage. Field experiments were established over three consecutive years in two areas of central and northern Greece. SL was determined as the percentage of damaged seeds, whereas the weight of the damaged seeds was estimated as YL. Farming system was the main source of variation for both SL and YL. Mean SL under organic farming was 15% and mean YL was 0.13 t ha^–1. SL and YL were 2.6- and 8.4-fold higher, respectively, under organic than conventional farming. Valuable genotypic variability was observed with respect to both SL and YL. Early flowering and small seed size were traits associated with low SL and YL. Among varieties, mean SL ranged from 8.5% to 29.2% and YL from 0.06 to 0.31 t ha^–1. Evaluation for high yield potential, indicating bruchid tolerance, revealed two types of promising varieties: varieties with high yield and low seed bruchid damage due to phenological escape, and varieties with high yielding potential despite the high SL and YL.