Two experiments were conducted to study the effect of replacing rice bran or fishmeal by fresh or dried mulberry leaves on digestibility and nitrogen retention of pigs. Inexperiment 1, a double 4x4 Latin square design in a 2x4 factorial arrangement was used tostudy the effect of graded levels of mulberry leaf meal (0, 15, 30 and 50% on a dry basis,respectively) in diets based on rice brans and broken rice on the N balance of eight youngcastrate male Mong Cai pigs with a mean weight of 15 kg. Mulberry leaf meal (MLM)contained DM 30.4% and in the dry matter: ash 16.9, crude fibre 20.1 and crude protein(Nx6.25) 25.4%, respectively. Feed intake was calculated to be 50 g DM/kg body weight.Although not significant, DM and organic matter digestibility appeared to increase withincreasing levels of dietary MLM. Organic matter digestibility was significantly better(P<0.05); N balance indices improved with the inclusion of MLM in the diet, and this effectwas significant for N retention (P<0.05) when expressed as proportion of the digested N. Inexperiment 2, six Large White castrate male pigs, weighing on average 15 kg, wereallocated according to a balanced change-over design, to two diets where mulberry leaves,either in milled of sun-dried or chopped off fresh, contributed about 45% of the total dailyN intake in iso-nitrogenous diets (Nx6.25, 13.7% on a dry basis). There were no significanteffects of treatment on DM, organic matter and N digestibility but dry leaves wereassociated with slightly lower digestibility values. N balance tended to be better in pigs fedwith fresh mulberry leaves compared to mulberry leaf meal. It can be concluded that inrice-based diets, it is possible to use mulberry leaves as the main protein source.Keywords: Digestibility, leaves, mulberry, pigs, protein.