The present study aimed to evaluate the efficacy of narrow-leaved lupine seeds (NLL) as a protein source in rabbit diets in terms of growth performance, digestive enzyme activity, nutrient digestion, and nitrogen excretion and retention. Different varieties of NLL (Boregine, Jowicz, and Rumba) were used as the replacement of soybean meal (SBM) in the present study. The control diet contained 60 g/kg SBM, and the experimental diets, containing 110 g/kg NLL, differed in the varieties used (Boregine, NLLB diet; Jowicz, NLLJ diet; and Rumba, NLLR diet). For the growth performance trial, 160 rabbits (Hyplus PS19 x PS 40; of both sexes; weaned at 32 days of age) were randomly allocated into 4 groups (40 rabbits per group) and fed one of the diets for a period of 42 days. In addition, 40 rabbits weaned at d 32 (Hyplus PS 19 x PS 40; 10 rabbits per diet) were used for the determination of the coefficients of total tract apparent digestibility (CTTAD) of the diets and to determine nitrogen balance and nitrogen retention. The proteolytic activity tended to be lower in rabbits fed the SBM diet than in those of the other rabbits. The CTTAD of the diets were not affected by the dietary treatments. The losses of nitrogen in faeces were not affected by the dietary treatment. There were higher losses of nitrogen in urine (P = 0.006) and also a higher total excretion of nitrogen (by 0.36 g/day; P = 0.013) in rabbits fed the NLLJ diet than in rabbits fed the other diets. Consequently, there was a lower nitrogen retention coefficient in these rabbits (P = 0.008). There was a higher average daily feed intake in rabbits fed the NLLJ diet than in other rabbits (P = 0.035). This corresponded with the worse FCR in rabbits fed the NLLJ diet than in rabbits fed the other diets.