This study was aimed to verify the water quality of Limoeiro stream, which is a small tributary of Cachoeira river, through the histopathological analysis of the liver of Hypostomus cf. unae. Forty seven specimens have been collected by electrofishing at two sampling points. The routine histological techniques have been used in the analysis. The most frequent histopathological changes were vacuolation of hepatocytes and rectillination of sinusoidal vessels; furthermore, hepatocytes were found to be irregularly distributed and had round and large nuclei surrounded by elongated sinusoid vessels. Analyses have shown that point 2 had worst water quality than point 1, as indicated by a higher occurrence of moderate and severe alterations. Results have revealed that Limoeiro stream had a reasonable water quality, but to perform a more precise analysis of this water body, more detailed studies that adopt different methodologies are essential.