Data, consisting of 4235 lamb records, obtained from the Foundation Afrino Sheep Stud at the Carnarvon Experimental Station, were used to investigate factors influencing birth weight, weaning weight, monthly body weight from five to 12 months, body weight at 18 months of age as well as clean fleece weight and mean fibre diameter at 16 months of age. Year/ season of birth, sex and birth/rearing status of the lamb as well as age of dam and age of lamb were significant (P < 0.01) sources of variation for clean fleece weight and body weight at all ages. Mean fibre diameter was significantly (P < 0.01) influenced by year/season of birth, sex and age of lamb. Significant (P < 0.01) two-way interactions were found between year/season and sex and year/season and weaning status. Least-squares means (kg) for body weight were 4.84 ± 0.04 at birth, 29.55 ± 0.31 at weaning, 39.27 ± 0.41 at eight, 52.32 ± 0.52 at twelve and 54.13 ± 0.55 at eighteen months of age. For clean fleece weight and mean fibre diameter, least-squares means of 2.01 ± 0.09 kg and 21.47 ± 0.09 micron were recorded. The results are compared to those reported in the literature.