BACKGROUND: Propofol and thiopental sodium are short acting drugs and used as intravenous anesthetics for oocyte retrieval. Anesthetics administered during oocyte retrieval can pass into the follicular fluids and exert a detrimental effect on oocyte fertilizability. The aim of this study was to investigate the exposed concentration and time effect of these drugs on fertilization and early embryo development in a mouse in vitro fertilization (IVF) model. METHODS: Mouse oocytes were exposed in vitro to propofol at 0 (control), 0.09, 0.45, 2.3, 4.5microgram/ml and thiopental sodium at 0 (control), 0.2, 1, 5, 10microgram/ml for 10, 30, 60 minutes, washed, and inseminated. Thereafter, fertilization was assessed. Subsequent in vitro development to the hatched embryo was monitored daily. RESULTS: We found a concentration and time dependent toxic effect of propofol on the fertilizability of oocytes and early embryo development. The fertilization rate of mouse oocytes exposed for 30 minutes to medium containing 0.09microgram/ml of propofol was significantly lower than the control. The fertilization and hatching rate of mouse oocytes exposed for 10 minutes to medium containing 0.45microgram/ml of propofol was not lower than the control. We did not find a toxic effect of thiopental sodium on fertilization, but the hatching rate of fertilized oocytes exposed to medium containing thiopental sodium was significantly lower than the control. CONCLUSIONS: We suggest that the oocyte retrieval procedure should be done as quickly as possible in order to limit the toxic effect of these anesthetics.