Among  domestic  animals,  cattle  and  horses  kept  on  pasture   and  fed with  hay  and straw   are  exposed most  prominently   to environmental pollution. Determination of the  sta- tus  of heavy  metals  in  bodies of horses is  important for two  reasons.  Firstly, it  helps  to assess  the  level  of environmental contamination. Secondly,  heavy  metals  can  have  consi- derable  influence  on animals living outdoors. The  aim  of the  study  has been to verify  whether  the  level  of Cr, Mn, Cu, Cd, Pb and Ni  in  the coat hair   and  cornified  structures of hooves may  differ between  horses maintained alternately  in  a  stable  and  on pasture  and living  outdoors all year  long,  with   Polish   Koniks  from  Mazury   (the  Masurian  Lake  District)   taken  as  an  example.  Possible  effects  of the  feeding  season and age of horses  were considered. ln  total,  35  Polish  Konik   horses  were examined,  either  kept  in a  stable-pasture   system  in Popielno  or outdoors in  Wojnowo. Sixty-two   samples  of summer  and  winter   coat hair,   28 samples  of hoof horn, as  well  as  10  samples  of pasture   plants   and water   were analyzed.   The  data were  elaborated  with   the  use  multi-factor   analysis of variance, T-Tukey-Kramer test  and  Pearson's   correlation. The  results   show  that  Polish   Konik horses bred  in Mazury   have  a  low  heavy  metal concentration  in the  coat hair  and hoof horn.  The  stablepasture   and  outdoor maintenance systems   hardly  differentiate  the  element  content,  whereas   the  winter   feeding  results   in an elevated  concentration  of the  elements  in  the  hair. Yearlings show  higher  Mn and  Cd content  than  mares  and  foals  at  foot. The dam's  impact on the  heavy metal  concentration in  the hair  and  hoof horn  in  their  foals  is  usually non-significant.