Reducing spoilage and indicator bacteria is important for microbiological stability in meat and meat products. The objective was to evaluate the effect of different doses of gamma radiation on the shelf-life of lamb meat, vacuum-packed and stored under refrigeration, by assessing the microbiological safety, physicochemical stability and sensory quality. Lamb loin cuts (Longissimus dorsi) were irradiated with 1.5 kGy and 3.0 kGy. The samples, including control, were stored at 1 ± 1 °C during 56 days. Samples were analyzed on zero, 14, 28, 42 and 56 days by their microbiological and physicochemical characteristics. Sensory quality was carried out on day zero. The results showed a reduction (p < 0.05) in the microbial load of the irradiated samples. The acceptance of lamb loins was not affected (p > 0.05) by the radiation doses. Thus gamma irradiation at 3.0 kGy was effective in reducing the content of microorganisms, without harming the physicochemical characteristics evaluated.