Background: Climatotherapy at the Dead Sea is effective for patients with psoriasis, atopic dermatitis, vitiligo, and other diseases. Although impressive improvement has been reported for patients with psoriasis, with a clearance rate of more than 80% after a 4-week stay, questions regarding the safety of this treatment have arisen. Objective and Methods: We compare the mean UVB radiation intensities absorbed by psoriatic patients undergoing a 4-week climatotherapy under supervision at the DMZ Rehabilitation Clinic of Ein-Bokek (The Dead Sea, Israel), with similar climatotherapy studies in Sweden and Switzerland. We also compare the climatotherapy radiation dosages with the UVB intensities absorbed by psoriatic patients in radiation cabins at seven university clinics. Results: According to our individually computerized DMZ protocol, a psoriasis patient with skin type IV is exposed during a 4-week climatotherapy to a mean 3.11 J/cm² (148 MED) of UVB, similar to that in Sweden and Switzerland. The range of the in-clinic annual phototherapy in the seven medical centers studied varied from 1.17 to 37.80 J/cm² (56 to 1800 MED). Conclusion: When all relevant factors are taken into account, the mean UVB exposure dose at the Dead Sea is one of the lowest reported for clearance of psoriatic plaques. (J Am Acad Dermatol 1998;38:447-52.)