The nutritive value  and wholesomeness of carrot are highly  appreciated owing to such biologically  active compounds as  carotenoids, vitamin C and mineral  compounds found  in its roots. ln   2007-2009,  field  experiments  were  performed on  the  effect  of foliar  fertilisation of carrot  with   magnesium  sulphate   during its vegetative  growth  on  selected  nutrients (total  carotenoids,  vitamin C,  mineral magnesium). The field experiment was set up in a split-plot design  with  three replications on light  soil,  of slightly acid  reaction,  low in available P and K forms and very  low in Mg. Magnesium was applied  in  rates of 0,45 and 90 kg MgO ha-1  by spraying  carrot  plants   with   a  3%  solution  during  their   intensive  growth in the vegetative  season,  accompanied  by  constant  N,  P,  K  fertilisation. The experiment   involved five  carrot  cultivars:  medium-late  Berjo,   and  late Flacoro, Karotan,  Koral   and  Perfekcja, all  characterized by good storage life. The content of selected  nutrients in  carrot  roots was determined immediately after harvest  and  after  six-month  storage  in a  traditional earthen mound. Foliar application   of magnesium   significantly  increased the nutritive  value  of roots of the  carrot cultivars after  harvest, raising   the content  of total  carotenoids,  vitamin C  and magnesium   in edible  parts. The  rate  of 45  kg  MgO  ha-1  was  most favourable. The  six-month  root storage  led  to  a  decrease  in  the  biologically active  compounds.  The recorded loss  (mean  for  cultivars and  fertilisation)  reached  20%  of carotenoids,  50%  of vitamin C and  1%  of magnesium.  The highest nutritive value  was  determined  for  roots  of the  cultivars  Karotan and Perfekcja and  the  lowest  one in  roots of cv. Flacoro.