This study was designed to determine the effects of using yeast autolysate and black cumin seed in laying hen diets on laying performance, egg traits, some blood characteristics and antibody production to sheep red blood cells (SRBC). A total of 112 Brown Nick laying hens, 23. wks of age, were allocated to one of 4 diet groups in 2 levels of yeast autolysate (0 and 2. g/kg, Saccharomyces cerevisiae, InteWall) and 2 levels of black cumin seed (0 and 15. g/kg, Nigella sativa L.) for 18. wks according to a 2 × 2 factorial arrangement. Each group was divided into 7 replicates of 4 hens each. The diets were formulated to be isocaloric and isonitrogenous. Dietary treatments did not affect body weight, feed intake, egg production, mortality, excreta moisture, interior and exterior egg quality characteristics, egg yolk triglyceride or yolk malondialdehyde concentration. Yeast autolysate supplementation improved (P < 0.05) egg weight and feed efficiency but the usage of black cumin seed in the diets decreased (P < 0.05) egg weight. Dietary yeast autolysate or black cumin seed decreased egg yolk cholesterol level, blood serum levels of cholesterol, triglyceride and aspartate amino transferase (AST) and increased blood serum levels of alkaline phosphatase (ALP) and antibody titers to SRBC. The ratio of monounsaturated fatty acids (MUFA) to saturated fatty acids (SFA) increased with black cumin seed. It is concluded that 2. g/kg yeast autolysate (Saccharomyces cerevisiae) or 15. g/kg black cumin seed (Nigella sativa L.) had beneficial effects on egg cholesterol content and humoral immune response. The usage of yeast autolysate also improved egg weight and feed efficiency. The significant interactions were found in egg yolk cholesterol and anti SRBC titer between the usage of yeast autolysate and black cumin seed. © 2012 Elsevier B.V.