The current status of the proficiency analytical testing (PAT) program was discussed. PAT, a collaborative effort of the American Industrial Hygiene Association and NIOSH, was designed to assist participating laboratories in improving their ability to analyze samples of occupational and environmental relevance. The program provided quality control reference samples to more than 1,300 participating laboratories in 17 countries. Each calendar quarter (round) reference samples consisting of mixtures of three metals, silica (14808607), asbestos/fibers and one to three solvents are mailed to the participating laboratories. The participants were evaluated for each analysis by comparing their reported results against acceptable values established for each sample. PAT round 127 was sent out in October 1996 to 1,331 participating laboratories. A total of 1,212 laboratories submitted results. Altogether, 327 laboratories were rated proficient for the metals analysis, 78 of 79 were rated proficient for the silica analysis, 976 of 1,027 were rated proficient for the fibers analysis, and 288 of 311 were rated proficient for the solvents analysis. PAT round 128 was sent out in January 1997. The organic solvents in this round were methylethylketone (78933) and methylisobutylketone (108101), the metals were cadmium (7440439), chromium (7440439), and lead (7439921), the silica sample had a coal dust matrix, and the fiber sample included amosite (12172735) and a man made fiber.