Organizations and governments globally are making great efforts to develop strategies to reduce population salt intake, and thus reduce the prevalence of hypertension and CVD. The objective of this study was to explore the perceptions and knowledge about salt, sodium and their effects on health of adults of middle income in the urban area of San José; in order to provide information for the development of educational strategies. Four hundred interviews to subjects between 40 to 55 years old, belonging to middle income socioeconomics strata, sub-divided into three levels (high, medium and low) were performed. Frequencies analyses were performed, and the Chi-square test was applied. We found that people felt that they are not at risk of developing hypertension regardless of the sub-middle socioeconomic strata (p > 0.05) and 68% of individuals did not consider that their consumption of salt and/or sodium was excessive. In addition, 70% of subjects had no knowledge about the relationship between salt and sodium, and an association (p < 0.05) between the sub-division of the socioeconomic status and knowledge about this relationship was found. Individuals had an average knowledge about the risk of excessive salt/sodium consumption and the benefits of reduced intake. It was concluded that there is a knowledge gap in subjects and there is a need for developing initiatives to reduce salt/sodium intake, shocking enough to make people be more aware of their risk and change their eating habits.