Huperzine Q (1) and N-oxyhuperzine Q (2). two novel irregular fawcettimine-type Lycopodium alkaloids were isolated from the CHCl3 fraction of the basic material of the whole plant of the Chinese medicinal herb Haperzia serrata. Their structures were determined as 13-epi-13beta,16-epoxydihydrofawcettimine (1) and N-oxy-13-epi-13beta,16-epoxydihydrofawcettimine (2) by means of spectroscopic studies and X-ray crystallographic analysis.