Urolithiasis has affected the mankind for long years. These stones cause progressive renal impairment. These patients usually present with characteristic loin pain, vomiting, and sometimes fever. Patients may also be asymptomatic at times. Urinary stones can be classified on the basis of their size, location, X-ray characteristics, aetiology, composition (Mineralogy) and risk groups for recurrent stone formation. AIMS AND OBJECTIVESTo evaluate the Preoperative and postoperative radiological and biochemical changes in renal calculus obstructive uropathy in patients with cortical thickness of minimum 4mm. MATERIAL AND METHODSAll patients who were admitted in Department of Surgery, Rama Medical College Hospital and Research Centre, Kanpur, UP with diagnosis of obstructive uropathy due to stone disease and operated upon were included in this study. RESULTSAfter 1 month and 3 months the relief in obstruction was studied by repeating the tests. It was found that urea, creatinine levels took about 3 months to get normalized. USG and IVP at 3 months showed complete normalization of hydronephrosis, however, at one month few cases still had hydronephrosis. CONCLUSIONUrea, creatinine levels along with USG and IVP form the basis of detection and management of obstructive uropathy. CT scan has a definitive role in few cases where urea creatinine levels are on higher side. Renal scan is mandatory in the cases of delayed/nonfunctioning on IVP. Nephrectomy should not be done without assessment of renal function (%) on renal scan. After definitive management of relief of obstruction by various methods, it takes about three months for normalization of kidney function. KEYWORDSUrea, Creatinine, Ultrasonography, Intravenous Pyelography, Renal Scan, Renal Stone. HOW TO CITE THIS ARTICLE:Gupta M, Saini P, Gupta P, et al. Radiological investigations, biochemical renal function tests and the changes after surgery in renal calculus obstructive uropathy.