A method of constructing a modified signal-flow graph, the H-graph, for sampled-data systems is formulated. This graph is obtained from the system graph by incorporating a maximum number of 3nedges for ann-sampler system, depending on the existence of paths between the input of the system and the samplers, and/or between the samplers. A set of rules to calculate the transmittances of these edges is framed. The transmittances of some of the edges in the system graph are modified. The output is obtained from the H-graph by Mason's formula. The concept of the signal-flow matrix has been extended to cover the sampled-data systems.