Between September 1984 and April 1987 a total of 150 patients underwent Nd-YAG laser iridotomy procedures at the Bristol Eye Hospital. Forty of these patients (27%) were treated for acute angle closure glaucoma (AACG), and three of them (7%) suffered recurrent AACG. Sixteen patients who had been treated for AACG have been challenged by a pharmacological provocative test introduced by Mapstone, with a total of 23 eyes being tested. A negative result was obtained in all cases. Provocative testing is recommended to help identify those at risk of recurrent AACG.