Maraging steel, an ultra high strength steel having high alloying elements and low carbon, finds its application in many critical components including military and aerospace. As the strength of a material increases its susceptibility to stress corrosion cracking (SCC) also increases. A study is carried out to understand the SCC behaviour of MDN-250, welded through gas tungsten arc welding (GTAW) and friction stir welding (FSW) process. Melting and re-solidification during GTAW of maraging steel results in formation of reverted austenite at prior austenite grain boundaries and dendrite boundaries, in the form of pool, due to alloying elements segregation. The interface of austenite pool and surrounding martensite matrix is the corrosion susceptible region. GTAW (fusion welding) process results in coarsening of grains at the weld and HAZ which is more prone to SCC. There is no segregation of the alloying elements; formation of reverted austenite is thus restricted in FSW. A very high strain rate deformation achieved through FSW results in very fine grain structure which cannot be achieved through any other welding process. Better SCC properties of FS-welded maraging steel can be attributed to the fine grain structure and absence of reverted austenite in form of pool.