Food frequency questionnaires (FFQ) are designed to assess habitual diet by asking about the frequency with which food items or specific food groups are consumed over a reference period. In this study, we have developed a FFQ to assess habitual dietary intake of healthy adults to estimate the quality of their nutrition and conducted a study to validate the developed FFQ against a three-day 24-hour recall. Second aim of the study is to establish the correlation between the FFQ to assess habitual dietary intake and a three-day 24-hour recall, in relation with participants' age and education level. FFQ used in our study was adapted from the Harvard Semiquantitative Food Frequency Questionnaire, consisted of 101 food items, divided into 9 groups. The 24-hour recalls were collected during one week (the same week when the FFQ was completed) and on each different day of the week (two weekdays and one weekend day). Both the FFQ and three day 24-hour recall were distributed to 100 healthy, employed subjects, 32 males (aged 39.73 +/- 14.02) and 36 females (aged 34.20 +/- 10.63). The results indicated that the developed FFQ is valid instrument to assess the habitual intake of energy and most of the nutrients in healthy adults in the Republic of Croatia, while men tended to have higher correlation coefficients than women and therefore a higher correlation of the FFQ with the three 24-hour recalls. Statistically significant correlations are not found between energy and nutrient intake based on the education level of the participants.