The relationship between pre- and post-weaning performance of lambs on Italian ryegrass was investigated by grazing lambs at different stocking rates. A positive correlation was found between both the pre-weaning stocking rate (P = 0.008) and weaning mass (P = 0.001) and the post-weaning average daily gain, where post-weaning stocking rate was not significant when related to animal performance. The correlation between the weaning mass in early August and the final mass of lambs in November, after 83 days on ryegrass, was highly significant (P = 0.001). Lambs stocked at a low stocking rate (20 ewes with lambs/ha) prior to weaning gained 13.3 kg, while lambs in the high pre-weaning stocking rate (36 ewes with lambs/ha) gained 11.9 kg during the post-weaning period. The smaller lambs, originating from pastures with heavy stocking rates, could not catch up on ryegrass pastures, in terms of mass gain, to achieve acceptable slaughter mass within a reasonable period of time. The optimum pre-weaning stocking rate for ewes and lambs/ha on ryegrass will depend not only on the weaning mass desired, but also on the marketing strategy of the producer for the lambs after weaning.