The  purpose  of the  study  has  been to determine  the  yield,  chemical composition  and nutritive value  of green  forage  from  di- and  tetraploid  forms  of red  clover  grown  in  different seed density  regimes.  The  yield  of green  forage was  analysed  in  the  first  year  of full use, in 2003  and  2004,  having  cut  the plants  in  the  early  inflorescence  phase  (1st  cut).  In green  forage  samples,  the following  were  determined:   basic  chemical  composition, concentration  of water soluble carbohydrates  (WSC), fibre fractions  (NDF, ADF  and ADL) and macronutrients  (P,  K, Mg,  Ca,   Na).  The  nutritive  value  of green  forage  was expressed according to the INRA 1988 system. The  yield  of green  matter   from the  tetraploid   cultivars Bona  and  Jubilatka was  higher  than  from  the  diploid cultivars Krynia  and  Parada. The cultivar Bona  distinguished itself  by its  highest average  yield  of green matter,  dry  matter, total  protein  and  net  energy. The  dry matter  content  was  the  most  variable green  forage quality   characteristic. In both years,   green  forage  from  the  diploid  cultivars  contained more dry  matter  than  the  one made from  the  tetraploid  varieties. At  the  same  time,  seed density did not have  any  significant  influence on the  differentiation  of green forage  yields. Green forage  from  the  two  diploid  cultivars  was  characterised  by a  similar  energy and protein value and a better fill unit value (better potential intake by ruminants). The concentrations  of phorphorus,  potassium  and calcium  in green forage from the diploid  forms were  slightly higher  compared  to  the tetraploid   forms,  unlike   the  level  of magnesium, which  was slightly lower. Irrespectively  of the  polidy  level,  the  concentration  of macronutrients, except phosphorus,  was  higher  in the  first   year  of the  study. Considering   the  nu- tritional requirements of animals, green  forage  from  the  analysed  red  clover cultivars  was characterised  by  an  inadequate  level  of magnesium,   deficient amount  of sodium  and  an improper  Ca:P   ratio.   The  results   suggest  that diploid  forms  of red  clover  can  potentially generate  a  higher  nutrititive value than  tetraploid  ones.