Aim. To determine the levels of 70-kDa heat shock protein (HSP70) in urine and anti-HPS70 antibodies (Abs) in serum and to assess their clinical and prognostic value in patients with different forms of chronic glomerulonephritis (CGN). Subjects and methods. Seventy-nine patients with CGN, including 15 with inactive nephritis (Group 1), 35 with active CGN and preserved renal function (Group 2), 14 with the highest CGN activity and transient creatininemia (Group 3), and 15 with persistent proteinuria and chronic renal failure (Group 4) were examined. ELISA was used to estimate urinary HSP70 levels and serum anti-HSP70 Abs in the examined groups. Results. The patients with active CGN were found to have higher excretions of urinary HSP70 and serum anti-HSP70 Abs. Urinary HSP70 excretion was significantly higher in the patients with transient renal function (Group 3) than in those from the other groups. At the same time, there was a decrease in serum anti-HSP70 Abs, which was a poor factor of persistent nephrotic syndrome despite immunosuppressive therapy (IST). Despite long-term IST, the nephrotic syndrome was persistent in 9 (60%) of the 15 patients with low serum Ab titers. At the same time, 8 (80%) of the 10 patients with higher serum Ab titers responded to IST during 9 months. Conclusion. The investigation demonstrates the great value of HSP70 as an index of the severity of lesion and the activation of kidney self-defense mechanisms in patients with CGN. Determination of serum anti-HSP70 Abs may be used to assess the prognosis of CGN.