Aims: The lipid phosphatase SHIP2 has been implicated in the regulation of insulin sensitivity, but its role in the therapy of insulin resistant states remains to be defined. Here, we examined the effects of an antisense oligonucleotide therapy directed against SHIP2 on insulin action in a dietary rodent model of the metabolic syndrome, the high fat fed (HF) rat. Methods: Whole body insulin sensitivity was examined by insulin tolerance tests before and after the intraperitoneal application of an antisense oligonucleotide (AS) against SHIP2 (HF-SHIP2-AS) or a control AS (HF-Con-AS) in HF rats. Insulin action in liver and muscle was assayed by measuring the activation of Akt and IRS-1/2 after a portal venous insulin bolus. SHIP2 mRNA and protein content were quantified in these tissues by real-time PCR and immunoblotting, respectively. Results: In HF-SHIP2-AS, whole body glucose disposal after an insulin bolus was markedly elevated when compared to HF-Con-AS. In liver, insulin activated Akt similarly in both groups. In muscle, insulin did not clearly activate Akt in HF-Con-AS animals, whereas insulin-induced Akt phosphorylation was sustained in SHIP2-AS treated rats. IRS-1/2 activation did not differ between the experimental groups. SHIP2 mRNA and protein content were markedly reduced only in muscle. In standard diet-fed controls, SHIP2-AS reduced SHIP2 protein levels in liver and muscle, but it had no significant effect on insulin sensitivity. Conclusions: Treatment with SHIP2-AS can rapidly improve insulin sensitivity in dietary insulin resistance. The long-term feasability of such a strategy should be further examined.