A method of reading data in a non-volatile memory device. The method includes reading a plurality of memory cells of a first page in a memory cell array using a first read level, reading a plurality of memory cells of a second page adjacent to the memory cells of the first page using a second read level, determining whether a state of each memory cell of the first page has been changed based on the first read level to verify a threshold voltage of each memory cell of the second page based on the second read level, and revising the state of each memory cell of the second page according to a result of the determination.