Objective: To estimate the validity of triage ratings by South African nurses and doctors with training and practical experience using the South African Triage Scale. Methods: Five emergency physicians and 10 enrolled nursing assistants, who had been trained in the use of the South African Triage Scale, were selected via convenience sampling to retrospectively triage adult emergency centre vignettes. Participants independently assigned triage ratings to 100 written vignettes unaware of the ratings given by others. Triage ratings were compared with ratings of two experts from the South African Triage Group. Standard validity indicators including sensitivity, specificity, positive predictive value and negative predictive value were used to estimate the validity for the combined group of emergency physicians and enrolled nursing assistants. Associated percentages for over-/under-triage were used to further assess validity within the South African context and over-/under-prediction to further assess practical application of the South African Triage Scale. Results: On average over all acuity levels, sensitivity was 75%, specificity 91%, under-triage occurred 10% and over-triage 15% of the time. The positive predictive value was 74% and negative predictive value 91%. Conclusion: The results of this study fall within the accepted range of over-/under-triage and indicate that the South African Triage Scale is valid when used by emergency physicians and nurses to triage emergency centre vignettes under South African conditions. Further research into appropriate reference ranges for extent of over-/under-triage and over-/under-prediction within each acuity level is recommended.