Abstract. Background: Catha edulis (Khat) is customarily chewed to attain a state of stimulation and reduce physical fatigue. In view of the reported common adverse effects of Khat, the aim of this study was to evaluate the levels of iron, ferritin, folic acid, vitamin B12 and body mass index (BMI) as nutritive indicators in Yemeni Khat chewers. Methods: This study was a prospective cohort study, carried out on 90 male workers aged 19 - 23 years old; 45 were healthy non-Khat chewers serving as control group and 45 were regular Khat chewers. Serum iron, ferritin, folic acid, vitamin B12 and body mass index were measured at baseline and after a year of follow up. Results: Serum iron and BMI were significantly (p < 0.01) lower at baseline in Khat chewers by 9 % and 6 %, respectively; whereas ferritin, folic acid and vitamin B12 were non-significantly different from non-Khat chewers. In the follow-up one year later, serum iron, ferritin, vitamin B12 and BMI were significantly (p < 0.001) lower in Khat chewers by 19.0, 31.4, 20.6 and 10.7 %; whereas folic acid was significantly (p = 0.007) higher by 26.7 %. Comparison within groups showed serum iron, ferritin, and BMI to be significantly (p < 0.01) decreased after one year in the Khat chewers with respect to its baseline; whereas folic acid significantly (p < 0.001) increased. Conclusion: This study shows Khat chewers to be more susceptible to malnutrition, which should be considered by the general population and the public health authorities.