ABSTRACT Purpose To perform the expansion, validation of the content, criterion and construct of an orofacial myofunctional assessment protocol for individuals with cleft lip and palate; and to define evaluation parameters for the instrument use. Methods The expansion of the instrument was performed based on the MBGR protocol; the items, sub items and possibilities of answers of the amplified instrument were analyzed for their clarity by seven examiners for the content validation.. Assessment parameters were developed for the use of the instrument in order to minimize the subjectivity. Four examiners compared the aspects of the protocol to those of another instrument for the criterion validation, and the construct validation was performed comparing the results of pre and post orthognathic surgery treatment. The Content Validation Index and the Kappa, Spearman and Wilcoxon Correlation tests were applied for the validations. Results The mobility, tonicity and sensitivity aspects of the evaluation were added to the protocol and at content validation, 72% of the items were classified as very clear and 28% as clear. A manual with assessment parameters for all items and sub items of the protocol was constructed. The inter-examiner agreement was moderate. In the comparison of the protocols, for the validation of the criterion, a good relation among them was observed. For the validation of the construct the protocol was able to identify outcome after the treatment. Conclusion The protocol was expanded and considered validated in its entirety: content, criterion and construct, and evaluation parameters for its use were established.