We present results of our combined X-ray and optical study of NGC 2451, which actually consists of two different stellar clusters situated along the same line-of-sight at distances of 190 and 360 pc, respectively. Based on ROSAT X-ray observations and on our extensive optical CCD BVR-photometry we are able to identify 113 stars down to spectral class M as member candidates of the two NGC 2451 clusters. Their general X-ray properties are consistent with an age in the range 50 to 100 Myrs. The nearer of the two clusters is especially interesting since it ranks among the ten nearest clusters and is supposed to be of lower metallicity than solar.