The diagnosis of the flows in a river basin is of great relevance for the knowledge of the modifications undergone in a given period, which is possible from a data collection of the historical series measured through the fluviométricas stations installed in a region. The present study had as its purpose to analyze the occurrence of flow trends in the hydrographic region of Calha Norte, in the state of Pará, using the non-parametric Mann-Kendall method and the Sen Slope indicator. The pluviometric and fluviometric data were limited in the period (1981 to 2007) due to their availability of the historical series, matching them, so that one could see the contribution of rain in the flow behavior. Information from 6 fluviometric stations and 6 corresponding rainfall stations, obtained from the National Water Resources Information System-SNIRH, from the National Water Agency-ANA (Hidroweb) were used. Thus, of the fluviometric stations analyzed in the hydrographic region of Calha Norte-PA, 5 presented tendencies to a significance of 5%, being the stations located in the municipalities of Monte Alegre, Óbidos, Almeirim and Oriximiná. Only the E.F2 station, located in the municipality of Alenquer, did not present a significant trend. On the correlation with rainfall stations, it was verified the existence of influences of the volume of precipitation in the described period, being noticed isolated peaks of flow, demonstrating abnormal behaviors, with influence of other variables, whether of natural order or not, what could be related to anthropic activities or critical climatic events occurring in the municipalities studied.