In a method of operating a semiconductor memory device, a program command is received, and a program operation is performed to increase threshold voltages of memory cells to be programmed by applying a program pulse to a word line. Page data is read from the selected memory cells by applying a verification voltage to the word line, and it is determined whether the number of memory cells corresponding to a program pass is greater than a determined number, based on the page data. A status fail signal is output based on the determination result.