Especially complicated, renal lithiasis contributes to the general inflammatory syndrome development that interferes with nonspecific, humoral and cellular immune system. The surgical treatment of nephrolithiasis is closely related to drug therapy of urinary infection, one of the reasons being the reduction of the immune status. The work is performed by evaluating the immunological status preoperatively in 58 patients with complicated lithiasis. The analysis of the status in these patients demonstrated that complicated urolithiasis results in significant changes in the immune system, these changes being expressed at the cellular and humoral level of immunity.