This study investigates the effects of long-term treatment with sulodexide (SLX) on norepinephrine (NE)-induced contractions, acetylcholine(Ach)-induced relaxations, acute cyclooxygenase blockade by diclofenac (DIC) in isolated femoral arteries (FA) and the parameters of oxidative phosporylation in liver mitochondria. 15-weeks old Wistar rats were divided into four groups: control (C; injected with saline solution), treated control (C+SLX), diabetic (DM) and treated diabetic (DM+SLX). Diabetes was induced with a single i.v. dose of streptozotocin (STZ) 45 mg.kg(-1). SLX was administered i.p., at dose 100 IU.kg(-1) daily for 5 weeks. Vascular responses of isolated femoral arteries were measured using Mulvany-Halpern myograph. Respiratory function of the mitochondria was determined using voltamperometric method on oxygraph Gilson. In diabetic rats the amplitude of maximal response to NE was elevated. DIC pretreatment decreased the amplitudes of NE-induced contractions in all groups of rats. SLX treatment decreased sensitivity of FA to NE and caused higher relaxatory responses to Ach in C and DM. Oxygen consumption and phosphorylation rates ([QO(2)(S(3))], [QO(2)(S(4))] and (OPR)) and respiratory control ratio (RCR) were decreased in the mitochondria of DM rats. Mitochondria of C rats were not affected with SLX treatment. Administration of SLX in DM rats was associated with increase of RCR, other parameters were not affected. Our findings suggest that SLX treatment might be associated with vasculoprotective effects during diabetes and improvement of mitochondrial function.