Smoking is a major risk factor for Urothelial carcinoma (UC). However the complex mechanisms, how smoking promotes carcinogenesis and tumour progression, remain obscure. A microarray based approached was therefore performed to detect the smoking derived gene expression alteration in non-malignant and malignant urothelial tissues from patients with superficial or invasive UC. Smoking enhanced cell migration and response to tissue damages. In non-malignant tissues smoking induced immune response and altered the cytoskeleton. In urothelial carcinoma, smoking altered extracellular and chromosome structures. Smoking affected tissues from patients with invasive carcinomamore strongly, up-regulating particularly growth factors and oncogenes in non-malignant tissue of patients with invasive but not with superficial carcinoma. In former smokers, comparable changes were seen in tissues form patients with invasive disease while they were minor or reversed in tissue of patients with superficial disease. Best but not complete tissue repair was suggestedfor non-malignant tissue from patients with superficial tumours. we used microarray techniques to define gene expression profile which may explain the contribution of smoking to urothelial carcinoma. Gene expression profiling using GeneChip HG-U133A Plus 2.0 (Affymetrix) was performed on non-malignant and carcinogenic urothelium from six patients with superficial and six with invasive urothelial carcinoma, each group including two current, former, and non-smokers.