There is a high prevalence of alternatively spliced genes (isoforms) in the human genome. Studies toward understanding aberrantly spliced genes and their association with diseases have lead researchers to profile the expression of alternatively spliced products. High-throughput profiling of isoforms has been done using microarray technology. Expression of isoforms reflects regulation both at transcriptional and posttranscriptional levels. This chapter details the methods to perform exhaustive comparison of isoforms using the R statistical framework.