Safety signs are very important communication tools for accident prevention, fire safety, health hazard information, and emergency evacuation. They are helpful when properly designed and understood by employees. The purpose of the present study was to investigate fiberboard industry employees' understanding of safety signs. 139 participants were asked to indicate the meaning of a series of 22 commonly used safety signs. The mean comprehension score for 22 signs was 66.6% (min. 22.5% and max. 98.6%). The mean score for warning signs was the lowest, prohibition signs was the highest. Poor comprehension score (less than 40%) was noted for the toxic material, automated external heart defibrillator, overhead obstacle, and disconnect mains plug from electrical outlet signs. These low comprehension scores indicate that some symbols may not effectively convey the message to the audience. Safety practitioners and trainers should pay more attention to teach the actual meaning of those signs.