Abstract: Real time RT-PCR was applied to compare the developmental expression patterns of IGF-Ⅰ, IGF-ⅠR and IGFBP3 genes in liver and muscle of Lantang and Landrace pigs at the ages of 1, 27, 90, 150 and 180 days. We have found: (1) IGF-Ⅰ gene was expressed at a higher level in liver than that in muscle. The highest level of IGF-Ⅰ mRNA was detected in muscle at day 90 compared with other ages in both breeds; however, the level of IGF-Ⅰ mRNA differed between breeds and the highest level was observed in liver at day 180 in Landrace and at day 90 in Lantang . (2) The expression level of IGFBP3 gene was higher in liver than that in muscle. the highest expression level of IGFBP3 was observed in muscle, at day 1 in both breeds. Significantly higher level of IGFBP3 mRNA at day 1 in Lantang were detected (P < 0.05); for Landrace, a significantly higher level was detected at day 1 than that at the days of 90, 150 and 180 (P < 0.05). However, expression of IGFBP3 differed between breeds in liver. Significantly higher expression level of IGFBP3 was observed in Lantang at day 90 than that at the days of 1, 27 and 150 (P < 0.05), whereas the highest level was found in Landrace pigs at day 150 among all ages, but the difference was not statistically significant. (3) In liver, the highest expression level of IGF-ⅠR was detected at day 27 in Landrace and at day 90 in Lantang. In muscle, expression level of IGF-ⅠR was higher at birth than any other ages and decreased with age in both breeds. (4) In total, Lantang showed highest expression levels of IGF-Ⅰ, IGF-ⅠR and IGFBP3 genes in liver, and IGF-Ⅰ gene in muscle at day 90, compared with other ages; while the highest levels of IGF-ⅠR and IGFBP3 genes in muscle were observed at day 1. Generally, the expression pattern of all three genes seemed to be similar in muscle of Landrace, with higher level at early age than that at later stage. There was no consistent varying expression pattern of all three genes in liver of Landrace.