Polyamines were found to modulate the activity of several membrane-bound enzymes, participating in cell growth and differentiation. We have studied the effect of polyamines (spermidine, spermine and putrescine) on rat mesangial cell ectoenzymes: 5′-nucleotidase, Mg<sup>2+</sup>-ATPase and Ca<sup>2+</sup>-ATPase. Ecto-5′-nucleotidase activity was significantly increased after 48 h treatment with spermine and spermidine. Mg<sup>2+</sup>-ATPase was increased only after treatment with spermidine; however, Ca<sup>2+</sup>-ATPase was significantly increased after both spermine and spermidine treatment of mesangial cells. Culture of mesangial cells with putrescine did not change the activity of these ectoenzymes. Increased expression of mesangial cell ecto-ATPase and ecto-5′-nucleotidase after spermine and spermidine treatment could result in an increased production of adenosine, a powerful autacoid interesting with respect to a role of mesangial cells in inflammatory processes.