The implantation-induced defects of crystalline silicon implanted with helium ions to a dose of 5 x 10(16)/cm(2) at 600 degrees C were investigated. The sample was analyzed by transmission electron microscopy and high-resolution electron microscopy. Faceted cavities are observed in the damaged layer. Concurrently the distribution of interstitial-type defect clusters was investigated by conventional electron microscopy in bright and dark field. Many rod-like defects, which belong to {1 1 3}, {1 1 1} and (- 2 0 0), are formed in the end of the projected range. In front of the damaged layer, some ribbon-like defects are formed, which belong to <2 0 0>, ,<1 -1 1> and <1 3 - 3>. The possible reasons of the observed defect clusters are discussed.