To identify long-distance transport durations compatible with acceptable animal welfare, the aim of this study was to determine the responses of healthy sheep to road transport under good conditions for 12, 30, or 48 h. Merino ewes (n = 120; 46.9 +/- 0.39 kg) were allocated to road transport treatments of 12, 30, or 48 h, with 2 replicates per treatment. Blood and urine samples and BW were taken pretransport and at 0, 24, 48, and 72 h posttransport. Lying time was measured using data loggers. Increasing transport durations resulted in reduced (P < 0.001) BW and increased (P < 0.05) hemoconcentration, but these effects did not exceed clinically normal ranges for any transport duration, and sheep generally recovered to pretransport values within 72 h posttransport. Sheep transported for 30 and 48 h had less BW on arrival than sheep transported for 12 h (P < 0.001). There were no differences (P > 0.05) between the 12- and 30-h treatments in sheep BW at 24, 48, or 72 h after arrival. Sheep transported for 30 and 48 h had greater total plasma protein concentrations on arrival than sheep transported for 12 h (P < 0.001). Although the white cell count and neutrophil:lymphocyte ratio increased with transport, there were no consistent effects of transport duration. There were also no effects (P = 0.10) of transport duration on plasma cortisol concentrations. There were no treatment differences (P > 0.05) in lying times during the first 18 h after arrival. Sheep transported for 30 or 48 h lay down less (P < 0.05) than sheep transported for 12 h between 18 and 24 h after arrival, but there were no other differences over 72 h. These findings indicate that healthy adult sheep, transported under good conditions, can tolerate transport durations of up to 48 h without undue compromise to their welfare.