Background: In recent years, increasing number of studies demonstrated the effectiveness of vitamin A on preventing some types of cancer. Although; Vitamin A is well known as fat soluble vitamin with marked beneficial effects for human health, there is a contradictoryevidenceregard its safety in cancerous cases. Purpose: Generally, excessive vitamin A levels had no preventive effect and in some cases were associated with increased cancer deaths. The proposed study aimed to highlight the importance of sufficient but not excessive intake of vitamins A by studding the potential preventing effect of taking vitamin A before the cancer illnesses and its harmful effect during the same illnesses. Experimental Design: Healthy 45 male Swiss albino mice were used. They were randomly divided into five groups (each with 5 animals) group I was the tumor group (T) without any olive oil or vitamin A treatments as a control group, the other four groups weretreated with olive oil and the olive oil-resolved daily recommended dose of vitamin A (0.2214 ?l) using different plans. Solid tumor was induced in all groups by intramuscular injection of Ehrlich ascites carcinoma (EAC) cells (2.5x106 cells/ mice) in their right thighBody weight and tumor size were recorded at 0, 2,3and 4 weeks and statistically analyzed. Expression levels of p53 and p16 genes studiesfor tumor tissuesweredone after 4 weeks. Results: significant differences in body weight were found between control groups (T) and all the other groups. Administration of olive oil (O) and vitamin A before and after solid tumor inductionfound to beinsignificantlydecreasedthe tumor circumferencescompared to untreated group (T) with differences between the effects of treatments in each group. Vitamin A and olive oil found to have some effects on the expression levels of P16, P53, TERT andVEGFAgenes. Conclusion: Administration of vitaminA by cancerous casesmustbecritically controlled. In the current study, vitamin A daily supplementation found to be not effective in controlling EAC solid tumor growth as evidenced by both gross and gene expressionexamination. Vitamin A supplementation must be avoided as it will act as pro-oxidant agents hindering the action of anticancer drugs.