<em>Pythium</em> species and environmental factors in various types of water bodies (2 springs, 2 rivers, 3 ponds and 6 different trophic lakes) were studied. Samples of water were collected every two months (springs, rivers, ponds) and every three months (lakes) in the years 1996-1999 for hydrochemical analysis and in order to determine the Pythium species content. From springs rivers and ponds collected were also ice blocks for determinations of presence of <em>Pythium</em> species. Buckwheatand hemp-seeds, cellophane and snake exuviae were used as bait. Forty-five species of <em>Pythium</em> were found in various types of water bodies. <em>Pythium acanthicum</em>, <em>P. complectens</em>, <em>P. complens</em>, <em>P. diameson</em>, <em>P. dissimile</em>, <em>P. elongatum</em>, <em>P. lucens</em>, <em>P. megalacanthum</em>, <em>P. nagae</em>, <em>P. oedochilum</em>, <em>P. oryzae</em>, <em>P. palingenes</em>, <em>P. periilum</em> and <em>P. polysporum</em> were recorded for the first time in Poland. The largest mean number of species was observed in spring Cypisek, a bit fewer in spring Jaroszówka and lake Białe (oligotrophic-like waters). The lowest mean number of <em>Pythium</em> species was noted in pond Akcent and Pałacowy (polytrophic waters). In all types of water bodies the higest mean number of species was found in winter, and the lowest in summer.