This paper presents the main results obtained during an ongoing experimental test program performed to explore the possibility of repairing structural cracks on adobe walls through the injection of mud-based grouts. The structural objective was to attempt to recover the original strength of severely cracked adobe masonry elements by repairing them with mud-based grout injections. Masonry strength was first estimated with indirect tension tests of adobe sandwiches and later measured with diagonal compression tests of adobe masonry small walls. It was decided to study the use of grouts prepared with sieved soil alone or stabilized with lime, cement, and gypsum. The test results showed that grout injections based on the original soil used to build the walls are effective in restoring completely the original strength of adobe walls which had endured significant seismic damage. It seems, therefore, that a new criterion for the conservation of earthen buildings in seismic areas could be formulated, using compatible materials for the restitution of the original seismic strength of the earthen structural elements. © 2008 Taylor & Francis Group, London.