Background/aim: Ultrasound biomicroscopy (UBM) is an important tool for assess ing anterior segment pathology. This study sought to evaluate UBM in the managem ent of anterior segment tumours. Methods: Retrospective analysis of medical reco rds of consecutive patients referred to the ocular oncology unit, University of California San Francisco (UCSF), for suspected anterior segment tumours from 199 9 to 2004. Results: 132 eyes from 130 patients were evaluated, including 55 uvea l melanomas (UM), 21 iris naevi, 30 iris cysts, and 26 remaining lesions. Of the melanomas, 45 were also evaluated with conventional A/B-scan. There was 29%co rrespondence between the anatomical structures invaded by melanoma as identified by B-scan v disease extent defined by UBM. Ciliary body and peripheral iris in volvement by melanomas was significantly more frequently observed by UBM than B -scan. Seven of 30 benign cysts were diagnosed as cystic before UBM evaluation. In three cases, neuroepithelial cysts were associated with intercurrent patholo gy including iris naevus (n=2) and ciliary body melanoma (n=1). Two ciliary body melanomas showed cavitation, including one patient with a pseudocyst. Histopath ological correlation was possible in six cases. Conclusion: UBM is an indispensa ble tool for the management of anterior segment tumours. This study demonstrates the superiority of UBM conventionalB-scan for the precise localisation of uvea l melanoma, especially involving the ciliary body and peripheral iris. Background / aim: Ultrasound biomicroscopy (UBM) is an important tool for assess ing anterior segment pathology. This study sought to evaluate UBM in the managem ent of anterior segment tumors. Methods: Retrospective analysis of medical reco rds of consecutive patients referred to the ocular oncology unit, University of California San Francisco (UCSF), for alleged anterior segment tumors from 199 9 to 2004. Results: 132 eyes from 130 patients were evaluated, including 55 uvea l melanomas (UM), 21 iris naevi, 30 iris cysts, Of the melanomas, 45 were also evaluated with conventional A / B-scan. There was 29% co rrespondence between the anatomical structures invaded by melanoma identified by B-scan v disease extent defined by UBM. Ciliary body and peripheral iris in volvement by melanomas was significantly more often observed by UBM than B -scan. Seven of 30 benign cysts were diagnosed as cystic before UBM evaluation. In three cases, neuroepithelial cysts were associated with intercurrent patholo gy including iris naevus (n = 2) and ciliary body melanoma (n = 1). Two ciliary body melanomas showed cavitation, including one patient with a pseudocyst. Histopath ological correlation was possible in six cases. is an indispensa ble tool for the management of anterior segment tumours. This study demonstrates the superiority of UBM conventional B-scan for the precise localization of uvea l melanoma, particularly involved the ciliary body and peripheral iris.