Background: The medically important desert-horned or Egyptian sand viper (Cerastes cerastes) is one of the most familiar snakes of the great deserts of North Africa and the Middle East. It is a poisonous and widely distributed snake in Africa and inhabits the sandy deserts of Egypt. Male and female specimens of C. cerastes have been compared from different aspects. Results:  Morphologically, tail length relative to snout-vent length was compared. Males significantly showed longer tails than do females. From the venom aspect, males showed a significant (p<0.005) higher concentration of protein in the venom (133mg/ml) compared to females (106 mg/ml). Female venom was significantly more toxic than male, with a median lethal dose (LD₅₀) in mice of 0.6μg venom protein/gm body weight whereas LD50 for males was 0.7 μg/gm. Protein analyses by means of electrophoretic technique revealed differences in venom composition between males and females. We have detected individual variability and highlighted sex-specific protein similarities and differences among snake venoms. SDS-polyacrylamide gel electrophoresis showed protein bands of 42 and 39 kDa specific to male venoms while bands of 46 and 44 kDa are specific to female venoms. Moreover, we evaluated the antitumor efficacy of male and female snake venoms in liver (HEPG-2), breast (MCF-7), colon (HTC-116) and normal cell lines and IC₅₀ was calculated. Interestingly, both male and female venoms had anti proliferative effects on the tumor cell lines with different potency. Female venom had a higher cytotoxicity against colon cells (IC₅₀=0.006 µg/ml) than male venom (IC₅₀= 0.019µg /ml). In contrast, male venom had a higher cytotoxicity against breast cells (IC₅₀=0.005 µg/ml) than female venom (IC₅₀=0.024µg /ml). These results indicate that males and females of C. cerastes produce venoms with different composition and activity, which may have epidemiological implications.