The objective of the study was to assess the effects of Na[V V O(O 2 ) 2 (2,2í-bpy)] ◊ 8 H 2 O (complex 1), Na[V V O(O 2 ) 2 (1,10í-phen)] ◊ 5 H 2 O (complex 2 ), Na[V V O(O 2 ) 2 (4,4í-Me-2,2í-bpy)] ◊ 8 H 2 O (complex 3 ), [ V IV O(SO 4 )(1,10í-phen)] ◊ 2 H 2 O, (complex 4 ), [ V IV O(SO 4 )(2,2í-bpy)] ◊ H 2 O (complex 5 ), where: 2,2í-bpy = 2,2í-bipyridine, 1,10í-phen = 1,10í-phenanthroline, 4,4í-Me-2,2í-bpy = 4,4í-dimethyl-2,2í-bipyridine and a small insulin injection on V, Cu, Mn, K, Fe, Zn, and Ca concentration in the STZ (streptozotocin) diabetic rats pancreas during a 5-week treatment with the tested complexes. In all groups of animals metal concentration in the pancreas was investigated by means of Proton Induced X-ray Emission (PIXE) method. Maximum con- centration of vanadium was observed in the pancreas for complex 5 (1.69 ± 0.09 mg/kg dry weight), lower for complex 3 (1.51 ± 0.10 mg/kg dry weight), and the lowest for complex 1 (1.21 ± 0.27 mg/kg dry weight) sup- plementation. The influence of vanadium administration on other metalsí concentration in the ratsí pancreas was also investigated. All vanadium-tested complexes showed an increase of zinc concentration in the exam- ined pancreas in comparison to the diabetic animals not treated with vanadium. The results were the highest for complex 1 and the lowest for complex 5. The concentration of Fe, Cu, Mn, K and Ca in the pancreas is not evi- dently influenced by administration of the vanadium complexe.