Because of the increasing cost of animal feed ingredients as well as the high demand, especially for the protein supplements, several efforts were carried out to use untraditional feed protein ingredients to participate in facing feed shortage problem and at the same time to decrease feeding costs. Nigella sativa (black cumin) and Thymus vulgaris are the most famous medical plants that have attracted the attention of many investigators for long time. The present study aimed to evaluate the possible effects of a partial replacement of soybean meal in control diet by Nigella sativa and/or Thymus vulgaris on the possible harmful changes in histological structure of some organs and blood parameters in growing New Zealand White rabbits. Blood constituents showed that the percentages of hemoglobin, hematocrate, the mean corpuscular hemoglobin and white blood cells (WBCs) count were significantly increased with the presence of black cumin seeds in the diets while WBCs count and the mean corpuscular volume in rabbit blood tends to decrease in Thymus vulgaris diets. Feeding diet supplemented with Nigella sativa increased the plasma total proteins, albumin, globulin, serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) and decreased total lipids, cholesterol and triglycerides. The use of Nigella sativa alone or either mixture with Thymus vulgaris are good supplements for growing rabbits without any adverse effect on histological structure of liver, kidney and testis in rabbits.