This report describes selected biological effects on transformed human cell lines and on rats from exposure to simulated maglev magnetic fields (MFs). Rats (n = 6 per group) were exposed at various times throughout the 24-h day to MFs simulating the de and complex ac components of the German TransRapid TR-07 maglev prototype vehicle. Expected ride times as long as 4 h and MF intensities from 50*1500 mG measured for the TR-07 were tested, up to MF levels predicted for superconducting magnet-powered maglev vehicle compartments (1 mG-1.75 G). Maglev-like HF exposures up to 7 times the intensity produced by the TR-07 had no effect on cultured growth of four human cell lines or on chemically Induced differentiation compared to control, unexposed cultures. Changes in the amount of rat pineal melatonin and serotonin-N-acetyItransferase (NAT), which have been shown by others to be decreased under a range of electromagnetic field (EMF) exposure frequencies and intensities, were not observed for TR-07-like MFs. Intermittent exposure to de-component maglev MFs (1-2 C) significantly depressed nighttime (control) levels of NAT, with weak effects on melatonin and NAT seen with 1- to 2-G-intensity intermittent (ac component alone) and continuous maglev (ac dc) MF exposures. These results should be further examined, since they suggest that ac component TR-07-like MFs and time-varying EMFs at superconducting maglev intensities produce biological effects.