Purpose: To compare the measurement of the basal diameter of choroidal melanoma, an important parameter for planning treatment and as a prognostic factor, by standardized ophthalmic ultrasound versus that obtained using a wide-angle fundus camera. Methods: The longest and shortest basal diameters of 104 consecutive choroidal melanomas of patients seen at the ocular oncology service of the Hadassah University Hospital were measured by B-scan ultrasound and compared with those measured by a wide-angle fundus camera (Panoret-1000). Each diameter was measured thrice by two ophthalmic photographers, and intra-observer and interobserver reproducibility were calculated as well. Results: The measurements of both the long and short diameters of the choroidal melanomas were significantly larger when measured by Panoret-1000 as compared with the B-scan ultrasound. There was no significant difference among the three measurements of each of the photographers. The interobserver reproducibility between the two photographers was high. Conclusions: Our findings can be attributed to the larger extent of the pigmentation of the melanoma compared to its recognized elevation. Since pigmentation of choroidal melanoma is easier to recognize than its elevation, we assume that measurement by a wide-angle fundus camera is more accurate in pigmented tumors, and should be adopted for measuring the basal diameter of choroidal melanomas in planning treatment and follow-up.