The main objective of this paper is to study the determinants of capital structure of SMEs in ?Vinho Verde? sector and the way that can influence their level of indebtedness. Through the multiple linear regression models methodology, it is studied the behavior of the capital structure determinants between 2003 and 2012, considering a sample of 13 ?Vinho Verde? SMEs obtained through the SABI data base. This study intends to examine the indebtedness level, with two main theories that practice the issue, the Trade-Off theory and the Pecking Order theory. The Trade-Off theory considers the existence of an optimal capital structure, a blend of equity capital and debt, capable of maximizing the firm value. Meanwhile, the Pecking Order theory suggests the existence of a hierarchy on the use of the financing resources. The obtained results suggest that lucrativeness, assets tangibility, firm dimension, general liquidity and other tax benefits besides debt and risk are those determinants that best explain the capital structure of the studied SMEs. The results of our paper allow to conclude that Trade-Off theory and Pecking Order Theory shouldn?t be considered isolated to explain the capital structure of ?Vinho Verde? SMEs.