The laboratories that participated in the proficiency tests GSR2005 and GSR2003, which were intentionally designed the same, show a noticeable improvement in the performance of the GSR2005 test. In contrast to this, laboratories that participated in the GSR2005 test for the first time, and which can be considered a "control group," show a lower detection capability rate. This suggests that a continuous participation in the proficiency test program leads to an improvement in the performance of the individual SEM/EDX systems, particularly for the detection of submicron GSR particles. This allows the laboratories to react to weaknesses in the performance of their systems based on the individual detection capabilities. This provides the opportunity for system optimization and validation, especially as the test sample remains with the laboratories after the test for further use. Seventy-five laboratories from 28 countries participated in the proficiency test and submitted 83 independent datasets. The participating laboratories were requested to determine the total number of PbSbBa-containing particles on a synthetic test sample following their own laboratory methods of automated GSR particle search and detection by SEM/EDX. Size and position of the detected particles had to be reported by the laboratories and were evaluated statistically. The results were compiled by means of z-score according to authorized guidelines. 2 tables, 4 figures, and 10 references