Leachates from a small sanitary landfill were examined paying attentions on the characterization of the colloids in the leachates by their size and the distribution of the metallic elements associated to the colloids in the leachates and the efflients from the treatment facility. Iron is the most abundant metallic element in the leachate. Its concentration is found to be from 0.4 to 4.0 mg/L. Heavy metals such as lead and cadmium barely exist as dissolved form. Most of the alkaline and alkaline-earth metal ions were fount in the filtrate collected through filter papers of which molecular cut-off size is less than 500. Most of the iron ions is associated to the colloids of lager size than those for the alkaline or alkaline-earth metals ions. It seems that most of chromium exists in association to the colloids of 0.45-2.8 μm in size. According to the result of chemical equilibrium computer model SOLMNQ, alkali and alkaline earth metals were predicted to exist primarily as uncomplexed free ions. But Pb and Cu were predicted to exist mainly as chloride complexed ions.