Although nanomaterials have the potential to improve human life, their sideline effects on human health seem to be inevitable and still remain unknown. This study aimed to investigate the cytotoxicity and genotoxicity of titanium dioxide (TiO2) and silver (Ag) nanoparticles (NPs) at different doses and particle sizes to bone marrow cells. Both types of nanoparticles were chosen due to their wide applications of them in consumer products. Rats were injected intravenously with a single dose of 5 or 10 mg/kg bw of 20 nm AgNPs or with 5 mg/kg bw 200 nm AgNPs or with 5 mg/kg bw 21 nm TiO2NPs. The samples were taken at 24 h, 1 week and 4 weeks following the exposure. Micronucleus test and the Comet assay were used to detect DNA damage. Neither AgNPs nor TiO2NPs caused cytotoxicity to bone marrow red and white cells. The polychromatic erythrocytes are the main target of both nanoparticles. A single exposure to AgNPs induced significantly enhanced frequency of micronuclei not only at 24 h after exposure, but also 1 and 4 weeks later, whereas single exposure to TiO2NPs showed positive effect at 24 h only. Negative responses were shown in reticulocytes (micronuclei) and in leukocytes (Comet assay) of bone marrow. Results indicated that different bone marrow cells display different susceptibility toward genotoxicity mediated by both investigated nanoparticles. The use of materials containing nanoparticles and the potential health implication of them should be monitored.