This dataset contains occurrence data of all butterfly species in the Netherlands on a 5 x 5 km scale for each year from 1994 up till 1999. It summarizes the observations recorded by hundreds of volunteers and professionals. Distribution maps in the latest Dutch butterfly atlas 'De Dagvlinders van Nederland' by Bos, F. et al. (2006) (ISBN 90-5011-227-7) were based on the same dataset. We are happy to share our data for research to strengthen butterfly conservation while respecting the input of our volunteer recorders. Researchers are thus encouraged to contact the dataset owner to collaborate on joint analyses and meta-analyses.