Aim: This study aimed to assess the effects of hygiene education on periodontal health and mouth/nasal halitosis in patients with cleft. Materials and Methods: 39 patients with cleft who were accepted for orthodontic treatment divided into two groups as with (Group1; n = 24) and without braces (Group2; n = 15). Plaque Index (PI), Gingival Index (GI), and Tongue coating Index (TCI) values were recorded. The BANA test microbiological kit, was used to determine the amount of anaerobic bacteria. Values of volatile sulfur components (VSC) for the measurement of oral and nasal halitosis were measured with a Halimeter device. After the initial measurements, oral hygiene instructions were given to eliminate the plaque production on teeth, periodontal structure, tongue and palate. All measurements were repeated 4 weeks after the hygiene instructions. Wilcoxon and Mann-Whitney U test were used for statistical analysis. Results: In both groups, the PI, GI, values were significantly decreased (P <.05). Tongue coating area, thickness and TCI were significantly reduced (P <.05). Oral halitosis values decreased significantly (P <.05). The PI values decreased significantly more in the Group 1 (P <.05). Non significant difference was detected in nasal halitosis in both groups. In unilateral cleft lip and palate cases cases (n = 23), no significant difference was found in nasal halitosis values between the cleft and the healthy sides (P > 0.05). Conclusion: In patients with clet cases, periodontal health was improved and oral halitosis was reduced by the given hygiene education; brushing the teeth, especially the tongue and palate. However, hygiene education did not have a significant effect on nasal halitosis. Key Words: Cleft lip and palate, Halitosis, BANA test, Periodontal index.