In this introductory talk, I will discuss current issues on protein folding problem. Proteins control basically all chemical processes essential for life and, for this reason, understanding the functional mechanism of a protein and the structure function relationship of a protein is one of the most fundamental issues in biological sciences. In recent years informatics-based approaches assisted with ever-increasing experimental data have served as practical tools for structure & function prediction of proteins. Similarly, much progress has been achieved in physics-based approaches. Strength and weakness of these two approaches will be discussed.