Nuclear excitation by electron transition (NEET) has been observed for Ir-193 in K-shell photoionization, following a previous measurement for Au-197. We detected internal conversion electrons emitted by decaying excited nuclei of Ir-193 in time spectroscopy using a silicon avalanche photodiode. The incident synchrotron X-rays were monochromatized and scanned around the iridium K-edge (DeltaE = 0 eV). At energies of between DeltaE = +105 and +344 eV, an increase of event rates due to nuclear excitation was observed at a level of 2.2-times higher than the standard deviation of the background measured at energies of between DeltaE = -3 and -324 eV. The NEET probability at DeltaE = +128 eV was obtained to be (2.8+/-0.4) x 10(-9), which is less than one tenth of the probability for NEET on Au-197. (C) 2004 Elsevier B.V. All rights reserved.