Genetic variability of six rhododendrons with contrasting local distribution patterns in Hong Kong was assessed by starch gel electrophoresis. Rhododendron championiae, R. hongkongense and R. simiarum are locally rare with disjunct distributions, R. moulmainense is restricted and R. farrerae and R. simsii are common. For each species, 13–18 allozyme loci representing 12–16 enzyme systems were scored. The six species showed similar levels of genetic variations (HT ranged from 0.209 to 0.386 and AT ranged from 2.4 to 4.1) which are high compared to plants with similar life history traits. Genetic structure, in contrast, varied greatly between species, with FST ranging from 0.056 to 0.393. The three rarest species had high genetic differentiation (FST and FPT) and distinct geographical patterns, while the other three had low differentiation and little or no geographical structure. These differences are attributed to both present distributions and historical changes following deforestation within the last 1000 years. The conservation implications of these results are discussed.