Aim: To assess whether the pre-surgical microbiology in a group of cleft lip and palate patients has an effect on the surgical outcome. Method: The study was undertaken over a two year period at the Royal Hospital for Sick Children, Yorkhill, Glasgow. Throat and nasal swaps were collected prospectively from all cleft lip and palate patients on the day prior to elective surgery. All swabs were processed in the on-site microbiology laboratory and the results were categorised according to culture findings into normal oral flora or a specific pathogen or pathogens. In addition, each patient's age, gender and surgical procedure were recorded. Each patient was assessed at review clinic and the surgical outcome was noted to be good or bad (dehiscence/fistula). The data was then analysed by a statistician and compared with the surgical outcome. Results: We will present the microbiological data from 188 cleft lip and palate cases treated in a two year period and demonstrate the association between microflora cultured / age / gender and surgical outcome, including the statistically significant relationship between poor surgical outcome and culture of haemophilus influenza from nasal samples. Keywords: cleft lip and palate, microbiology, haemophilus influenzae, screening