In an evaluation of safe, inexpensive, orally administered contrast agents for use at magnetic resonance imaging, different concentrations of the clay agents kaolin-pectate and attapulgite were compared in an in vitro phantom by performing spin-echo imaging with variable echo times to estimate T2 relaxation time. Additional phantoms containing from 0% to 100% attapulgite or barium preparations were compared by using spin-echo and spoiled-gradient-echo techniques to estimate T1, T2, and T2* relaxation times. In vivo spin-echo and gradient-echo images were obtained of 10 healthy volunteers and of five patients with pancreatic disease after oral administration of 12-16 oz of attapulgite preparation. T1 and T2 relaxation times obtained with use of attapulgite were slightly lower than those obtained with kaolin-pectate at both 50% and 25% concentrations. Compared with barium, attapulgite had shorter T1, T2, and T2* relaxation times, and concentration-dependent relaxivity was greater by nearly an order of magnitude. All subjects were able to drink the attapulgite, and the only complaints were of bad taste and mildly loose stools.