The pathophysiology of human chronic pancreatitis is not well understood and difficult to follow on a molecular basis. Therefore, we used a rat model (WBN/Kob), which exhibits spontaneous chronic inflammation and fibrosis in the pancreas. We compared gene expression patterns in the pancreas during development of inflammation and fibrosis of WBN/Kob rats with age-matched healthy Wistar rats using microarrays. The extracellular matrix protein SPARC (secreted protein, acidic and rich in cysteines) and other transcripts of inflammatory genes were quantified by real-time PCR and some localized by immunohistochemistry. When pancreatic inflammation becomes obvious at the age of 16 weeks, several hundred genes are increased between 3- and 50-fold in WBN/Kob rats compared to healthy Wistar rats. Proteins produced by acinar cells and characteristic for inflammation, e.g. pancreatitis-associated protein (PAP), are highly upregulated. Other proteins, derived from infiltrating inflammatory cells and from activated stellate cells (fibrosis) such as collagens and fibronectins are also significantly upregulated. SPARC was localized to acinar cells where it increased in the vicinity of inflammatory foci. However, acinar expression of SPARC was lost during destruction of acinar cells. In human pancreatic specimens with chronic pancreatitis, SPARC exhibited a similar expression profile. During chronic inflammation and fibrosis in the WBN/Kob rat, inflammatory genes, growth factors and structural genes exhibit a high increase of expression. A temporal profile including pre- and post-inflammatory phases indicates a concurrent activation of inflammatory and fibrotic changes. Inflammation dependent expression of SPARC appears to be lost during acinar-to-duct metaplasia both in rat and human pancreas.