The purpose of this paper is to determine by experiment whether Mn11Si19 and Mn4Si7 in their bulk states have a finite magnetic moment or not. Magnetisation measurements were carried out on these materials using both SQUID system and Kerr rotation system. The high quality samples were grown using the temperature gradient solution growth method. SQUID measurements revealed that Mn11Si19 has finite magnetism while Mn4Si7 does not in their bulk states. It was also confirmed that Mn4Si7 became magnetic and Mn11Si19 got to exhibit a distinctive hysteresis in their powdery state. The enhancement of magnetism implied that the surface of the samples was to a great extent linked to its magnetism. (C) 2011 Elsevier B. V. All rights reserved.