This study analyzes the design and implementation of various forms of architectural elements, the use of panels, materials, color resolution up to technical details that Alvar Aalto used for the natural light and illumination of interior spaces in buildings designed by him. Firstly are analyzed some of the most important buildings designed by Alvar Aalto. Furthermore types and shapes of windows for natural lighting are demonstrated in graphic ways, showing the efficient use of natural light in different seasons of the year and different positions of the sun. The aim of the research is to identify the details and methods used in natural light in the illumination of the interior spaces of different objects as libraries, museums, etc. This study is important because it gives conclusions about the use of architectural shapes with its various elements and the use of natural light for an efficient lighting in the interior spaces of buildings.