This study evaluated the acute toxicity and biokinetics of intravenously administered silver nanoparticles (AgNPs) in mice. Mice were exposed to different dosages of AgNPs (7.5, 30 or 120 mg kg−1). Toxic effects were assessed via general behavior, serum biochemical parameters and histopathological observation of the mice. Biokinetics and tissue distribution of AgNPs were evaluated at a dose of 120 mg kg−1 in both male and female mice. Inductively coupled plasma–mass spectrometry (ICP-MS) was used to determine silver concentrations in blood and tissue samples collected at predetermined time intervals. After 2 weeks, AgNPs exerted no obvious acute toxicity in the mice. However, inflammatory reactions in lung and liver cells were induced in mice treated at the 120 mg kg−1 dose level. The highest silver levels were observed in the spleen, followed by liver, lungs and kidneys. The elimination half-lives and clearance of AgNPs were 15.6 h and 1.0 ml h−1 g−1 for male mice and 29.9 h and 0.8 ml h−1 g−1 for female mice. These results indicated that AgNPs could be distributed extensively to various tissues in the body, but primarily in the spleen and liver. Furthermore, there appears to be gender-related differences in the biokinetic profiles in blood and distribution in lungs and kidneys following an intravenous injection of AgNPs. The data from this study provides information on toxicity and biodistribution of AgNPs following intravenous administration in mice, which represents the worst case scenario of toxicity among all the different administration routes, and may shed light in the future use of products containing AgNPs in humans. Copyright © 2012 John Wiley & Sons, Ltd.