The influence of smoke on THz imaging was examined. We tested experimentally a passive THz camera - TS4 from ThruVision Systems Ltd. The camera detects natural human radiation at a frequency of 0.25THz. The distance camera-target could be 3-15 meters. Moreover, Time Domain Spectroscopy was used to investigate the influence of the amount of smoke on transmission in the (0.1 ÷ 2.5)THz range. Full Text: PDF References H. Zhao, Advanced Materials Research 490-495 (2012). CrossRef L. Yun-Shik, Principles of Terahertz Science and Technology (Springer 2008).CrossRef M. Sypek, M. Makowski, E. Hérault, A. Siemion, A. Siemion, J. Suszek, F. Garet, J.L. Coutaz, "Highly efficient broadband double-sided Fresnel lens for THz range", Optics Letters 37 (12) (2012) CrossRef N. Palka, "THz Reflection Spectroscopy of Explosives Measured by Time Domain Spectroscopy", Acta Physica Polonica A 120 (4) (2011). CrossRef N. Palka, M. Szustakowski, T. Trzcinski, M. Mozdzonek, Photonics Letters of Poland 3 (2) (2011). CrossRef ThruVision System Ltd., website: http://www.truvision.com Teraview Ltd., website: http://www.teraview.com