Highlights
•  The novel coronavirus (2019-nCoV) pneumonia has caused 2033 confirmed cases, including 56 deaths in mainland China, by 2020-01-26 17:06.
•  We aim to estimate the basic reproduction number of 2019-nCoV in Wuhan, China using the exponential growth model method.
•  We estimated that the mean R 0 ranges from 2.24 to 3.58 with an 8-fold to 2-fold increase in the reporting rate.
•  Changes in reporting likely occurred and should be taken into account in the estimation of R 0.