Certain components of the metabolic syndrome, such as hyperglycaemia, hypertension and dyslipidaemia, have been reported in recent studies to correlate to benign prostatic hyperplasia (BPH). Although obesity represents an important parameter of the metabolic syndrome also, its association with BPH remains controversial. The aim of this study is to summarize the existing literature concerning the coexistence of obesity and BPH, and to elucidate whether an association between these conditions exists. We identified studies published from 1980 onwards by searching electronic databases, such as MEDLINE. Initial search terms included ‘benign prostatic hyperplasia’, ‘epidemiology’, ‘risk factor’, combined with ‘metabolic diseases', ‘hypertension’, ‘hyperinsulinemia’, ‘dyslipidemia’ and ‘obesity’. There are several observational and epidemiological studies examining the effects of obesity on BPH, though more studies examine the association between several metabolic or lifestyle factors and BPH. Evidence suggests that an association between BPH and obesity is possible. However, obesity exhibits a stronger positive correlation with BPH when its effects on BPH are examined in combination with other disorders which constitute components of the metabolic syndrome. When the effects of obesity on BPH are examined separately a confounding relation is demonstrated. As the common pathophysiological pathway between metabolic syndrome, obesity and BPH continues to be poorly highlighted, the exact relation of obesity and BPH remains unclear.