The relationship between the amino acid sequence and the three-dimensional structure of proteins with internal repeats is discussed. In particular, correlations between the amino acid composition and the ability to fold in a unique structure, as well as classification of the structures based on their repeat length, are described. This analysis suggests rules that can be used for the structural prediction of repeat-containing proteins. The paper is focused on prediction and modeling of solenoid-like proteins with the repeat length ranging between 5 and 40 residues. The models of leucine-rich repeat proteins and bacterial proteins with pentapeptide repeats are examined in light of the recently solved structures of the related molecules.