SUMMARY
The article aims at proposing a hybrid model to evaluate language complexity of source and target texts written both in English and Portuguese so that one can analyse at what extent language complexity has been transferred from a text to its translation. In it, hybrid model points to paralleled approaches to lexical repetition, lexical diversity and lexical density, readability and word unusualness with the help of some Corpus Linguistics tools. It also stands for developing adjustments to Paul Nation’s word family lists and Gunning’s GFI formula so that they can be applied to Portuguese language. Aiming at checking the reliability of the model, the article also presents a case study based on contrastive investigations on “The Secret Garden” by Burnett and its translation into Portuguese “O Jardim Secreto” by Perota and Carvalho.