Buildings after completion at times develop cracks which serve as a sign of failure of the building structure. The objectives were to identify and rank the various types of cracks in buildings and their related causes to know the various effects of cracks in building structures. The study adopted a quantitative structured questionnaire survey. Respondents were selected using purposive and random sampling technique. The same size for the study was 103 respondents made up of 5 professionals in building construction. Relative Importance Index (RII) was used to analyze both causes and effects. The study revealed that the ten (10) major causes of cracks are: permeability of concrete, freeze/thaw, natural forces, moisture movements, elastic deformations, temperature variations, among others. It was identified that: Some penetrate cracks on the wall can reduce performance, especially affect the building?s usage and seismic performance. The study recommends that the structural engineers must ensure good structural design and specifications by considering all the environmental aspects that include soil (Geotechnical) investigations that will enable the designer to come up with a proper design of the foundation. Since, buildings are designed for particular uses, and to withstand a given measure of weight (loading) for example a building designed as a residence will have different structural specifications from the one designed to operate machinery.Proper consideration and supervision must be put in place to ensure good mixing of building materials such as cement, sand, and aggregate. It is always important to take good care of thebuildings by doing maintenance works after a lapse of certain periods. This will keep the building intact and also extend their life span. Keyword: Investigation, Causes, Effects, Cracks, Building, Structures