Artemisinin has received much attention in the treatment of malaria in recent years, and it is now considered as a potential candidate to reduce coccidial infection in chickens. It is a sesquiterpene compound which has been isolated from Aretemisia annua for the first time. The present study aimed to investigate the occurrence of artemisinin in A. sieberi (AS) and to test the anticoccidial effects of plant extract in broiler chickens. The aerial parts of the plant were collected during different seasons from Yazd Province, in the centre of Iran. The artemisinin content of the AS was extracted with petrol ether and analysed by high-performance liquid chromatography using UV detection. Anticoccidial effects of the plant extract were tested on chicks challenged with various species of Eimeria. The infected chickens were treated with doses of 1 or 2.5 mg/kg per day artemisinin via oral administration of plant extract. The analytical results showed that the level of artemisinin in AS was 0.2% and 0.14% of dried weight (DW) of plant materials in summer and autumn, respectively. Treatment of experimentally infected chickens with AS extracts showed that artemisinin was able to reduce the severity of coccidial infection induced by Eimeria tenella and E. acervulina, but not E. maxima. The anticoccidial effects of artemisinin were shown by significant decrease in output of number of oocysts per gram of faeces in chickens challenged with different species of Eimeria. This study showed that the levels of artemisinin in AS were comparable with those in other species including A. annua, and that the extract of this plant can reduce coccidial infection in broiler chickens.