Case histories of Oliguria caused by block to urinary catheter, hypotension, renal artery spasm, and Rhabdomyolysis are described. Pathophysiology of Pre-renal, Renal and Post-renal Oliguria are described. Physical examination of a case with oliguria is described. Assessment of Input-out chart and the role of intravenous fluids, diuretics and Dopamine in management of oliguria are described.