Eventhough the sanitary latrine construction promotion program has been implemented for years, the latrine using rate is still far behind the target. Thus, this research was mainly aimed at the studying the efficacy of predisposing, enabling and reinforcing factors on the sanitary latrine using among rural families in Phitsanulok province. The research design of this study was cross-sectional study. Structure interview questionnairs were used to collect the data needed from 400 housholds in Self-reliance Primary Health Care Villages, Prompiram district, Phitsanuloke. The Kendalls b, Pearsons Product Moment Correlation and Multiple Classification Analysis (MCA) statistics were employed to analyse the relationship between the three group of factors mentioned above and the sanitary latrine using behavior. The results of this study revealed that seven in ten variables of the predisposing factors were significantly related to the latrine using behavior of the rural thai families. These factors were a period of residency in the community, number of the family member, educational level of the head of the household, the highest level of education of the family member, family income, the amount of information received, and the beliefs regarding to diarrheal diseases and latrine using. It was also found that among the predisposing variables, the most influencing factors was the amount of information received, the followed by beliefs and the income respectively. The least influencing factors was the educational level of the head of the household. The significant relationship between the three variables of the enabling factors namely

the experience in using the latrine, the perception about the easiness in using the latrine, and the easiness in cleaning the latrine-and the behavior was found. These variables were ranked according to its influencing power. Among eleven reinforcing factors, it was found that, nine variables were significantly related to the behavior. They were:- the discussion among the family members about the latrine using

the opinion of the family leader and the member regarding the latrine using

the experience of the relatives in using the latrine

the receiving of advice about the latrine from the elderly in the family, neighbores, public health workers, community council members and sanitary craftman. It was also found that the opinion of the family leader, the public health workers advice, and the experience of the family members in using the latrine were ranked first, second, and third in predicting the latrine using behavior. It was surprisingly found that the reinforcing factors was the most influencing factors, followed by the enabling and predisposing factors on sanitary latrine using among the rural families in Prompiram district, Phitsnuloke.