Relevance of the work is connected with the need for flow diagnostic at adaptive interpretation of unsteady hydrodynamic studies of horizontal wells using analytical models of pressure recovery curve. The main aim of the study: to develop a method of adaptive interpretation of the pressure recovery curve which allows diagnosing streams at hydrodynamic studies of horizontal wells with simultaneous evaluation of reservoir filtration characteristics. The methods used in the study: the theoretical and practical developments in the field of well testing, system analysis, system identification in light of additional prior information, optimization of functions and linear algebra were used. Solution of the problems of flon diagnosing, pressure recovery curve identification and interpretation has catried out on the basis of production data of downhole pressure in the well with the filter expert estimates of formation parameters using a computer program Saphir. The results. The authors have developed the adaptive method for interpreting the pressure recovery curve with the diagnosis of radial and linear flow with simultaneous assessment of filtration parameters of the oil reservoir at hydrodynamic researches of horizontal wells. By the example of processing the results of flow testing by the pressure recovery curve of two horizontal wells of uniform-porous oil reservoir it was shown that the adaptive method allows increasing the reliability of determining the time of radial and linear flow starts.