We here report a case of squamous cell carcinoma of the lung, with an unusually fast tumor growth rate, so fast that its early detection was impossible even with two sequential chest roentgenograms taken only 36 days apart. Literature related to the concept of cell growth kinetics was reviewed, and the tumor volume doubling time that characterizes any measurable tumor was calculated for our case accordingly, based on the single lesion found on the plain chest film, with the best possible estimation of its volume. We concluded that, to the best of our knowledge, a squamous cell carcinoma of the lung that grew so fast (with a tumor doubling time less than 7.5 days) has not yet been reported to date; neither has a bronchogenic carcinoma of any cell type been reported with such a presentation. Given that a patient aged 81 belonged to a group usually with slower growth in tumor cell kinetics, the behavior of his tumor was indeed uncommon.