Abstract- 230 Th, 232 Th, 234 U and 238 U compositions of several deep-sea solitary corals, mainly the species Desmophyllum cristagalli, were determined by thermal ionization mass spectrometry (TIMS). It is possible to obtain high precision ages on modern pristine corals that have low [ 232 Th] (5 to a few hundred ppt). However, because older deep-sea corals tend to have higher [ 232 Th] compared to surface corals, and the initial 230 Th/ 232 Th ratio is uncertain, older deep-sea corals have larger age uncertainties (Ϯseveral hundred years for samples with a few thousand ppt 232 Th). Therefore, the key hurdle for precise U-Th dating is to remove or account for contaminants which contain elevated 232 Th and associated 230 Th not due to closed system decay within the coral lattice. A modification of the trace metal cleaning methods used for foraminifera and surface corals can significantly reduce this contamination. By counting the visible growth bands and measuring the mean age of a single septum, the extension rate of D. cristagalli was estimated to be between 0.1 and 3.1 mm/year. In a mean sense, bands appear to be precipitated annually, but this estimate has a large uncertainty. If appropriate tracer calibrations can be established, these corals are therefore suitable to record decadal or sub-decadal oceanographic changes over the course of their lifetime. The ␦ 234 U values of all modern samples from different localities and different depths are similar (mean 145.5 Ϯ 2.3‰) and indistinguishable from the data obtained from surface corals. At a precision of about Ϯ2‰, we find no structure in the oceanic profile of ␦ 234 U ratios over the top 2000 m of the water column.