The laser flare-cell photometer was introduced as an instrument to measure anterior chamber inflammation (protein concentration and particle concentration, "cells") quantitatively and non-invasively. Thirty-two eyes with and without intraocular inflammation were examined using the laser flare-cell photometer by three different examiners under the same conditions to determine the reproducibility. The coefficients of variation of flare (Vfi) and of number of cells (Vci) were calculated for each eye (i). The median of the 32 coefficients of variation Vfi was 0.2; the median of the 32 Vci was 0.4. Furthermore, the median of the 32 flare (Mf1-Mf3) and number of cells (Mc1-Mc3) as measured by each examiner (U1-U3) were calculated. Another coefficient of variation could be calculated from Mf1-Mf3, which lay at 0.05, and from Mc1-Mc3, which lay at 0.13. The measurements of flare and number of cells with the FC-1000 have a good reproducibility if the average flare and number of cells in a group of patients are examined. This is one of the important conditions if, for example, the effect of two different drugs on two groups of patients are compared. In individual cases the laser flare-cell photometer can only be used together with further clinical examination.