Biofortification of vegetables with iodine can become an alternative method to salt iodization of introducing this element to human diet. Iodine is not an essential nutrient for plants and its effect on plant growth and development has not yet been sufficiently examined. The aim of the study was to assess the influence of soil fertilization with iodine (in the form of I– and IO3–) and nitrogen (applied as NO3– and NH4+) on the effectiveness of iodine biofortification as well as mineral composition of carrot storage roots. Carrot cv. Kazan F1 was cultivated in a field experiment in 2008 and 2009.  Different soil fertilization treatments with iodine as well as nitrogen were tested, including: 1 – control without N and I fertilization; 2 – KI fertilization without N application; 3 – KIO3 fertilization without N application; 4 – KI + Ca(NO3)2 fertilization; 5 – KIO3 + Ca(NO3)2 fertilization, 6 – KI + (NH4)2SO4 fertilization, 7 – KIO3 + (NH4)2SO4 fertilization. Iodine as KI and KIO3 was applied pre-sowing in a dose of 2 kg I ha–1. Nitrogen fertilization in the form of Ca(NO3)2 and (NH4)2SO4 was performed pre-sowing and as top dressing with 100 kg N ha–1. In carrot storage roots, the iodine content as well as P, K, Mg, Ca, S, Na, B, Cu, Fe, Mn, Zn, Mo, Al, Cd and Pb concentration were determined by the ICP-OES technique, while nitrogen – using Kjeldahl method.  Better results of iodine enrichment in carrot were obtained after introducing this element in the form of KI, especially together with ammonium sulphate. Application of the IO3– form of iodine significantly improved nitrogen utilization from mineral fertilizers by carrot plants. In storage roots of carrots cultivated without N nutrition, iodine treatment (in both forms: KI and KIO3) contributed to a significant increase in P, K and Ca content as well as a reduction in Fe accumulation. However, it had no influence on the concentration of Mg, S, Cu, Mn, Zn, Mo, Al and Pb in carrot storage roots. Application of KIO3, in comparison to KI, resulted in a significant increase of the K, Fe and Zn content in carrot roots fertilized with Ca(NO3)2. In the case of (NH4)2SO4 as a nitrogen source, KIO3 contributed to significantly higher accumulation of P, K, Mg, S, Na, B, Cu, Fe, Mn, Al and Cd in carrot storage roots when compared to KI.