We introduce a new Monte Carlo model for avascular tumor growth. The model is intendedrnto be as realistic as possible and is cell based model. We have developed a twodimensionalrnlattice Monte Carlo model. The model is complemented by key features suchrnas the explicit presence of nutrient diffusion and consumption, cell growth, cell divisionrnand cell death, and the cell-cell interaction. Tuning the parameters of the model can leadrnto the growth of different tumor morphologies, and can lead to different growth dynamics