Two hundred and sixteen (108 Hisex Brown; 108 Warren Studler) laying hens were given one of 12 dietary treatments. These were four basic diets with 0, 200, 400 and 600 g added cassava kg−1 and each basic diet was further subdivided and ZnO added to provide 100 and 200 mg Zn kg−1. None of the production traits measured was significantly affected by either added cassava or ZnO but there was a quadratic response in food intake to added cassava. ZnO addition significantly improved egg quality (assessed by Haugh score) but did not affect shell thickness. Haugh score was significantly affected by added cassava, the responses being significant after 2 weeks storage. The interaction between Zn level and cassava level significantly affected egg quality.