Freshly-harvested roadside grass, with and without a supplement of leucaena, was fed ad libitum to eight groups of five young Javanese Thin-tail rams at Ciawi, West Java, Indonesia. The experiment was a 2 × 2 × 2 factorial, involving supplementary sodium (NaCl), selenium (intraruminal pellet) and drinking water. Grass alone provided a sub-maintenance diet; during this period of the experiment the weight loss of the Se-supplemented sheep was half that of those not supplemeneted with Se (P < 0.05). The provision of 200 g leucaena dry matter daily, in addition to the grass, gave live weight increases. In this period the weight gain of animals supplemented with Na was twice that of those not receiving Na (P < 0.001). In both periods of the experiment the availability of drinking water had no influence on weight gain. The routine provision of supplementary NaCl appears to be advisable in this environment. The low digestibility of roadside grass is probably a major limitation to production.