Cell-mediated immunity (CMI) was evaluated in 40 children with idiopathic nephrotic syndrome and 20 healthy controls. The significantly decreased response to purified protein derivative (PPD)(P < 0.001), absolute lymphocyte count (ALC) (P < 0.02), T-lymphocytes percentage (P < 0.001) and elevated serum adenosine daminase (ADA) activity (P < 0.001) were observed in patients with active nephrotic syndrome (ANS) in comparison to controls. The overall mean values of T-lymphocytes percentage and ADA activity in ANS patients were 73.7 and 213.7 per cent of normal mean, respectively. A significant negative correlation was observed between the two parameters (r = -0.5649, P < 0.001). In remission, the ALC and T-lymphocytes percentage showed significant increase in levels in comparison to their corresponding ANS values (P < 0.05 and P < 0.001, respectively), but the latter remained significantly lower when compared with controls (P < 0.001). The ADA activity did not differ significantly in comparison to corresponding ANS level. Thus, impaired CMI was observed both in active, as well as in remission stage of the disease and ADA activity demonstrated a more pronounced change than other parameters.