Cocoa Bean Shell (CBS) is a waste product from cocoa processing industries, with attendant disposal problem. The level to which CBS can be utilized by layers was evaluated. The Raw CBS, (RCBS), Enzyme Rovabio Treated CBS (ECBS) and CBS Fermented by solid state (FCBS) were evaluated for their contents of Crude Protein (CP), Crude Fiber (CF), Ether Extract (EE), Metabolisable Energy (ME) and Theobromine. Total of 140 laying hens at 6-week in lay was used in this experiment with 20 birds per treatment, replicated twice. The experimental design is completely randomized design. The experiment lasted for eight weeks. Hen Day Production (HDP), internal and external egg quality characteristics were monitored. Data were analyzed using ANOVA. This study investigated the effect of treated cocoa bean shell based-diets on serum biochemistry and hematological parameters of layers. The variation observed in the total protein was significant while the variations observed for serum biochemical indices like albumen, globulin and creatinine were not significantly different among the dietary treatment. Fermentation and addition of enzymes reduced theobromine contents to 0.72 and 0.81 respectively while the highest value was recorded for RCBS (0.85). Hematological indices were not significantly different, however, highest serum total protein values (5.16g/dl) was observed in birds fed control diet. Enzyme-treated cocoa bean shell effectively replaced up to 10% maize in layers’ diets.