OBJECTIVES : To score dental arch development using the Great Ormond Street, London, and Oslo (GOSLON) yardstick index, following primary surgery in patients with a complete unilateral cleft lip and palate (UCLP), and to compare the outcome score with the GOSLON score of Cleft Care UK (CCUK) as well as with the Clinical Standards Advisory Group (CSAG), United Kingdom. METHODS : Study models of patients (average age 12 years) with a non-syndromic complete UCLP, who had been surgically treated at the University of Pretoria Facial Cleft Deformity (UPFCD) clinic. They were assessed using the GOSLON yardstick index by certified raters from the Dental School in Dundee, Scotland. The mean outcome ratings were calculated from the scoring of 27 sets of plaster models. The other scoring rounds were used to calculate intra- and inter-observer agreement using Cohen's weighted kappa and Fleiss's multi-rater kappa. RESULTS : There were strong intra- and inter-observer agreement, with a weighted kappa of 0.92. The Facial Cleft Deformity (FCD) clinic data showed a good treatment outcome with a mean GOSLON rating of 2.85 compared to a rating of 3.2 for the CSAG and 2.62 for the CCUK cohort studies. CONCLUSION : The UPFCD clinic primary surgical protocol displayed a good treatment outcome rating, in line with that of the CCUK cohort and better than the CSAG results.