The results of rounds 116 through 119 of the Proficiency Analytical Testing (PAT) Program conducted by the American Industrial Hygiene Association and the Centers for Disease Control and Prevention were reported. Samples were sent by the PAT program to participating laboratories each calendar quarter to evaluate the proficiency of individual laboratories in chemical analyses. Of the 1,379 laboratories evaluated in PAT round 119 conducted in October, 1994, 93.2% were found to be proficient. PAT proficiency ratings for the calendar year of 1994 based upon rounds 116, 117, 118, and 119 demonstrated an overall proficiency rating of 94% for all participating laboratories. The highest percentage of nonproficient laboratories were seen in rounds in which samples contained organic solvents followed by those with samples contaminated with metals. The most recent PAT round, number 120, sent to laboratories on January 3, 1995 was described as was a major change made to the organic solvents of the PAT program.