The increasing prevalence of obesity is a major public health concern, affecting more than one third of the Swiss population. The renal effects of obesity per se, independent of hypertenison or diabetes, though, are less known. Obesity is positively correlated with proteinuria and the development of glomerulomegaly and focal segmental glomerulosclerosis. The pathophysiology of the obesity-associated kidney disease is complex, including hemodynamic and physical factors and increased synthesis of vasoactive and fibrogenic substances by adipose tissue. The most important therapeutic approach is weight reduction. Angiotension converting enzyme (ACE) inhibition is effective in reducing proteinuria, but longer follow-up is required to determine the long term benfits of ACE inhibition.