Sprague - Dawley rats were used to study the effects of insulin on theapo AⅠ, CⅡ and CⅢ gene expressions. Using ³²P-labelled apo AⅠ, CⅡ and CⅢ recombinant DNA as probes, we determined the mRNA amounts of apo AⅠ, CⅡ and CⅢ in the liver and intestine of rat injected with insulin (1.5U/Kg weight of rat) by dot blot hybridization method. After injecting insulin, the mRNA amounts of apo AⅠ in liver and intestine were obviously decreased, to a lowest level (42%) at 6 h interval and restored to that of control group at 24h interval. Also, after injecting insulin, the mRNA amounts of apo CII in liver and intestine were declined remarkably, to a lowest level (57%) at 12h interval, still lower than that of the control group (79%) at 24h interval. But the mRNA amounts of apo CIII showed no significant changes after rejecting insulha both in liver and intestine when compared with the control group (P＞0.05). The experiment was repeated.12h after injecting insulin, the mRNA amounts of apo Al, CII and CIII in liver and apo A1 and CII in intestine were obviously decreased (45%, 51% and 54%, 35% and 37%, respectively, P＜0.01, n=5) and the mRNA amounts of apo CIII in intestine remained unchange (P＞0.05, n= 5). These resulls revealed that insulin could evidently affect the gene expression of apolipoproteins.