Objective: To utilize complementary biochemical and dietary data collected before the initiation of national flour fortification to (i) identify micronutrient insufficiencies or deficiencies and dietary inadequacies in Palestinian women and children in vulnerable communities and (ii) assess the suitability of the current wheat flour fortification formula. Design: Quantitative dietary intake questionnaires were administered and fasting venous blood samples collected in randomly selected households in Gaza City and Hebron. The impact of fortification was simulated by estimating the additional micronutrient content of fortified wheat flour. Setting: Households in Gaza City and Hebron that were not receiving food aid from social programmes. Subjects: Non-pregnant women (18-49 years) and children aged 36-83 months. Results: The micronutrients with highest prevalence of insufficiency were vitamin D in women (84-97 % with serum 25-hydroxyvitamin D <50 nmol/l) and vitamin B 12 in women and children (43-82 % with serum B 12 <221 pmol/l). Deficiencies of vitamin A, Fe and Zn were also of public health concern. Current levels of wheat flour fortificants were predicted to improve, but not eliminate, micronutrient intake inadequacies. Modification of fortificant concentrations of vitamin D, thiamin, vitamin B 12 , Zn and folic acid may be indicated. Conclusions: Micronutrient insufficiencies or deficiencies and intake inadequacies were prevalent based on either biochemical or dietary intake criteria. Adjustments to the current fortification formula for wheat flour are necessary to better meet the nutrient needs of Palestinian women and children.