Abstract: This study examines the preference level for the use of interlocking masonry over the conventional types in housing delivery in Nigeria. The study summarizes and interprets findings from a comparative survey carried out empirically among some practising professionals in the building industry on some residential projects selected from 4 out the 6 geo-political zones in Nigeria through the use of questionnaire, direct observations, photo prints and interview schedules. Research variables investigated include: cost of masonry works, time of setting of blocks and willingness to use the materials. In addition, two-way Analysis of Variance (ANOVA) was used to test for the presence of significant difference in the level of willingness of respondents to use the selected materials for future projects and material price ratings. Findings signify shorter time of construction and reduced cost of construction expended when interlocking blocks are used. The preference for the use of interlocking masonry in housing delivery as compared with the use of conventional blocks was also investigated. The study concludes that interlocking masonry is a good replacement to the conventional types in construction of housing in Nigeria.