Urine is a promising resource for potential biomarkers. Assessment of the posttranslational modifications (PTMs) is critical when studying protein function/activity, folding, and molecular interactions in relation to disease. Most of the researches on urinary proteome concentrate on the changes in the expressional level of proteins. However, many important biological processes are controlled not only by the relative abundance of proteins but also by PTMs. Modification-specific enrichment techniques, coupled with high-resolution mass spectrometry, have greatly enhanced the ability to identify confident PTMs in urine. Enrichment or visualization of proteins with specific posttranslational modifications provides a method for sampling the urinary proteome and reducing sample complexity.