We aimed to compare eventual biological effects in cellular cultures after X-ray irradiation. Human amnyocytes and rat peritoneal macrophages, irradiated with 3 Gy (G II) and 6 Gy (G III) were compared with a non-irradiated control (G I) over time. Both cell lines were isolated and cultured under aseptic conditions (37°C, 5% CO2). Cell proliferation and radiation cytotoxic effects were studied with the MTT test Cytogenetic evaluation of amnyocytes was done at 4, 24, 120 and 144 h post-irradiation, showing a correlation between the decrease of the survival rate and the increase of the irradiation intensity, although with some recovery capacity. For rat peritoneal macrophages the 6 Gy were also more harmful, killing the majority of the cells. The 3 Gy dose, although aggressive, enables a higher survival rate.