The epidemiological and clinical features of primary herpes simplex virus ocular infection in 108 patients were studied. Of these, 69 (64%) were aged 15 or over and only eight (7%) were under the age of 5. Associated upper respiratory tract infection was found in 38 (35%) patients and systemic disorders such as mild malaise, fever, and aching in 34 (31%) patients. Common symptoms were redness, watering, discharge, itching, irritation, and lid swelling, whereas pain, photophobia, lid vesicles and ulcers, and blurred vision were less frequent. The major signs consisted of vesicles and ulcers on the lids, papillary responses which were more severe in the upper lid conjunctiva, follicles which were more common in the lower lid conjunctiva, fine and coarse epithelial punctate keratitis, and subepithelial punctate keratitis. Dendritic ulcers and disciform keratitis were found in 16 (15%) and two (2%) patients respectively. The clinical forms of primary herpes simplex virus ocular infection varied. Moderate or severe disease was observed in 41 (38%) and 16 (15%) patients respectively. In eight (7%) patients the disease presented as an acute follicular conjunctivitis without characteristic lid or corneal lesions. A chronic blepharoconjunctivitis which lasted for months developed in 16 (15%) patients. The epidemiological and clinical features in our patients were compared with features of the disease reported previously.