Purpose: This study was done to identify the relationship among knowledge, attitude, internal health locus of control, and performance related hand washing among elders. Methods: Participants were 197 elders. Data were collected from October to December 2014 and analyzed using descriptive statistics, t-test, ANOVA, Pearson correlation coefficients, and stepwise multiple regression. Results: Mean scores for knowledge, attitude, internal health locus of control, and performance related hand washing were above average. The level of knowledge was significantly different according to gender and marital status. Attitude differed according to age, religion, and marital status. Internal health locus of control differed according to religion, and experience of education programs. Performance differed according to gender, religion, marital status, and leisure activities. Significant correlations were found between attitude and performance related hand washing, and between internal health locus of control and performance related hand washing. Attitude and internal health locus of control were predictors of performance related hand washing. Conclusion: These findings indicate that changes in perceived attitude and internal health locus of control may be necessary to improve practice related hand washing among elders. The results of the study can be utilized in health promotional programs for elders.