During 2010, the CMS experiment at the Large Hadron Collider collected a total integrated luminosity of 36 pb-1 at a center-of-mass energy of 7 TeV. With this initial data set, precise measurements of the standard model at the new ener gy regime have been performed, for example the measurement of the W and Z cross sections, and more recently the top pair production cross section. Now, CMS is engaging in the search for new physics beyond the standard model. The top quark sector is sensitive to new interactions due to the strong Yukawa coupling. For example, new massive particles can be produced which decay to a pair to top quarks. I will describe briefly the measurement of the top pair cross section in lepton+jets events, and in more detail the search for heavy top pair resonances in CMS.