In experiments carried out in 2005-2008 the influence of irrigation and cultivation system (organic, integrated and conventional), on the yields and economic effects of pea cultivation was investigated. It was stated larger increases of seed yield, protein in seeds and total protein yield in biomass of plants in integrated and conventional systems, in comparison with organic one, under irrigation conditions than under control conditions. Irrigation, on average for the cultivation systems, increased seed yield by 1,59 t/ha (119,5%), straw yield by 0.80 t/ha (18,9%), protein yield of seeds by 285,5 kg/ha (83,2%) and total protein yield of seeds and straw by 303,9 kg/ha (43,4%). Yields of seeds and their protein from integrated and conventional systems were similar and distinctly larger in comparison with organic one. In case of straw the yields increased with increasing of intensity in cultivation systems. Productivity of 1 mm of irrigation water was larger in systems of higher intensity of cultivation.. Irrigation decreased the protein content in seeds and straw. The most profitable, with taking into consideration adequate payments for systems, in both water variants turned out cultivation according organic system. Irrigation, on average for the cultivation systems, increased the direct surplus, without diminishing by irrigation cost, by 1611,7 PLN/ha.