Coxidin®, containing 25 % of the active substance monensin sodium, is intended to be used in the control of coccidiosis in chickens reared for laying up to a maximum age of 16 weeks, at the same doses as presently authorised for use in feedingstuffs for chickens for fattening (100–125 mg/kg complete feed). Concerning exposure and susceptibility to Eimeria infections, the FEEDAP Panel does not see essential differences between the two categories of the same animal species, chickens for fattening and chickens reared for laying. Both are in the same physiological stage of early growth. The FEEDAP Panel extended therefore its conclusions on the safety and efficacy of monensin from Coxidin® in chickens for fattening to chickens reared for laying. The FEEDAP Panel considers Coxidin® as safe for chickens reared for laying at a maximum dose of 125 mg monensin sodium/kg feed. It is not expected that Coxidin® at the maximum dose of 125 mg monensin sodium/kg feed will pose a risk for the environment. Monensin sodium from Coxidin® is efficacious in controlling Eimeria infections in chickens reared for laying at a minimum dose of 100 mg monensin sodium/kg complete feed.