Three surgeons operated on upper eye lids of northern Omani villagers for trichiasis due to trachoma using a standardised protocol. The lids were graded as minor trichiasis, five or fewer lashes; major trichiasis, six or more lashes; and lid closure defect. Operative success was defined as no lash/eyeball contact and complete gentle lid closure. One hundred and sixty five lids with major trichiasis were allocated by random number tables to one of five operations: bilamellar tarsal rotation (Ballen), tarsal advance and rotation (modified Trabut), eversion splinting (grey line), tarsal advance (lid split), and tarsal grooving (Streatfield-Snellen) operations. Bilamellar tarsal rotation was significantly more successful than eversion splinting (chi 2 = 7.0, p less than 0.01); tarsal advance (chi 2 = 12.4, p less than 0.001), and tarsal grooving (chi 2 = 23.7, p less than 0.001), but not significantly more successful than tarsal advance and rotation (chi 2 = 2.9, p greater than 0.05). Two of 32 (6%) lids with lid closure defect were successfully treated with tarsal advance; trichiasis was relieved in nine and lid closure defect in 10. It is suggested that bilamellar tarsal rotation and tarsal advance and rotation are effective operations for major trichiasis, but tarsal advance is ineffective where trichiasis and lid closure defect coexist.