The residue levels of three kinds of organochlorines, BHC, DDT and PCB, in the serum were determined in farmers (40-59 years old, n=211), non-farmars (40-59 years old, n =27) and high school students (15-18 years old, n=56) to clarify the factors that contributed to the accumulation of those three compounds in the blood of farmers and rural inhabitants. The average values of those compounds were found to be 9.1±5.0 ppb for B-BHC, 9.2±6.3 ppb for pp'-DDE and 7.1 ±5.7 ppb for PCB. There was marked difference in the value between districts in which the subjects live. The subjects could be divided into the lower concentration group and higher concentration group, showing high discrimination ratio (72-83%) by Hayashi's quantification theory II. Statistical analysis showed that the factors contributing to the accumnlation of those compounds in the present subjects are related with digestion of chicken and fish, Hb concentration, serum cholinesterase activity, liver function and serum trigliceride and cholesterol levels, and use of organochlorines and other pesticides, duration and the mumber of days of pesticide spraying, experience of pesticide poisoing, cultivation of specific crops. Those results, in greater part, supported the general recognition that organochlorine residues in human body might be regulated by changning eating patterns and avoiding those food items containing those chemical compounds. On the other hand, attention should be focused on the exposure of those compounds through the use of specific pesticides including those compounds. And further investigation is necessary for clarifying the contributing factors to the accumulation of those compounds in human body especially in the higher residue group discriminated in the present study.