In a traffic system, traffic signs are intended to convey messages to regulate, warn, and guide various types of road users like vehicle drivers, cyclists, and pedestrians. The safe and efficient use of the road system depends on all road users to understand and follow the meanings of traffic signs. It is interesting to know whether the first idea that comes to mind when viewing a sign associates or not with the sign's original meaning. The aim of this experiment was to study the guessabillity of pre-users for traffic signs. Forty-one Hong Kong Chinese subjects who did not take any driving tests before, nor possessed any driving licenses in any places participated voluntarily in this experiment. For minimization of any influence of daily encounters or prior experience with the testing traffic signs on the testing results, instead of using the signs currently used in Hong Kong, 120 traffic signs stipulated in the latest National Standards of the People's Republic of China for Road Traffic Signs and Markings (GB5768-1999 issued in April 1999) were employed. The results showed that guessing performance of subjects varied greatly from sign to sign. The mean and standard deviation of guessability score for all signs were 54.81% and 29.16%, respectively. The signs with extremely low guessability scores provided meaningful implications for designing traffic signs. The population stereotypes, sign familiarity, sign concreteness, and semantic closeness are probable factors affecting guessability of traffic signs. Further research efforts will be given in investigating whether the probable factors have effects on the guessability of traffic signs. The results would provide useful information and recommendation for designing more user-friendly traffic signs, which should reduce the training time of sign use for road users.