Natural language processing (NLP) deals with the interaction of computer and human language. Algorithmic model of NLP helps the computer to understand the human language, interpret it and then generates the response. It can handle both the written and oral form of language and can translate oral language into written form and vice versa. In health care & medical applications, NLP can extract structured data such as in a particular tumour it can extract information on tumour types, grades, morphological details, prognostic factors. The NLP typically uses deep learning particularly recurrent neural network. There are several challenges to implement NLP in routine practice in cytology such as unstructured data, complexity of data and privacy concerns. The current chapter discusses the basic principles and applications of NLP in computational cytology.