Lexical inferencing is one of the most important strategies in vocabulary learning and it plays an important role in dealing with unknown words in a text. In this regard, the aim of this study was to determine the lexical inferencing strategies used by Iranian EFL learners when they encounter unknown words at both text and sentence levels. To this end, forty lower intermediate students were divided into two groups. For the first group, a text with 10 underlined words was given and for the second group, the same underlined words were given in separate sentences. The students were supposed to read the text and the sentences and to guess the meaning of the underlined words. Then some lexical inferencing strategies were given to them to determine which strategies they used in guessing the meaning of unknown words. The results showed that they used different strategies like using local context and word association in lexical inferencing and also they were more successful at the text level than the sentence one. The results also indicated that they were strategic learners using their own strategies including translation and cultural background knowledge to guess the meaning of the unknown words.