An integrally shielded transportable 201Pb leads to 201Tl generator system for the production of 201Tl has been developed at the Crocker Nuclear Laboratory, University of California, Davis. The present generator design allows for processing of up to 4 Ci of 201Pb parent radioactivity yielding approximately 400 mCi of 201Tl in a chemical form easily converted to radiopharmaceutical quality. Larger capacity generator systems can be constructed since the use of depleted uranium for shielding purposes is becoming readily available. While the parent 201Pb radioactivity decays to the daughter 201Tl, the combination depleted uranium-lead shielded system (approximately 33 kg) can be transported to distant locations for final processing. In this manner, decay losses (approximately 25%) associated with transportation of bulk 201Tl can be avoided since transportation would occur during the time (approximately 32 h) needed for the growth of 201Tl via 201Pb(9.4 h) leads to 201Tl (73.5 h). Single small-volume elutions (15-20 ml) provide more than 95% of the 201Tl radioactivity with no detectable radioactive Pb breakthrough and less than 20 micrograms/ml of carrier Tl.