The diabetic organism is unable to produce normal amount of granulation tissue which results in delayed wound healing, a significant clinical problem. In the present study, the effect of oral administration of aminoguanidine (AG), in the diabetes-induced inhibition of angiogenesis and granulation tissue formation was tested. Subcutaneous implantation of sponge discs in nondiabetic rats induced a wound repair response as determined by the amount of hemoglobin (vascular index) and granulation tissue formation (morphometric analysis) of the implants. In the streptozotocin-induced diabetic rats the predominant response indicative of healing was inhibitory. Aminoguanidine was effective in preventing in 50% the diabetes-induced inhibition of fibrovascular tissue growth in the implants, as indicated by the values of hemoglobin content and vascular growth areas of the implants. These results indicate that AG holds potential therapeutic value in the management of healing impairment of the diabetic condition.