The mediastinum harbors a mixed bag of tumors, which may create significant diagnostic dilemmas. These tumors have widely variable therapeutic and prognostic implications. Correct pre-operative cytological diagnosis may obviate the need of surgical excision of many of these lesions. A stepwise algorithmic approach such as clinical history, radiological localization, salient cytomorphology and ancillary test helps in correct diagnosis of these tumors. This paper discusses the stepwise diagnostic algorithm for fine needle aspiration cytology diagnosis of mediastinal tumors.