This paper examines the relationship between firm characteristics and the timeliness of financial reporting in listed non-financial companies on the Istanbul Stock Exchange (ISE) from 2003 through 2010. The descriptive analysis indicates that the mean reporting lag is 83 days which is within the allowed period. Multivariate regression analysis shows that high-leveraged companies and companies with consolidated financial statements are late reporters. Our results suggest that companies audited by a Big 4-firm, companies whose audit reports were unqualified and companies that did not change their auditors were early reporters. No significant association was found between the company size, profitability, financial year-end, industry type and reporting lag. Our results provide policy makers and auditors with empirical evidence on the causes of the reporting lag, thereby increasing their awareness and helping them in their decision making process.