The elastic state of rod-shaped Ag precipitates in disc-shaped aggregates parallel to {100} planes in Cu−5.7 wt% Ag alloy single crystals has been studied. The rod-shaped precipitates have an elongated shape along a ⟨011⟩ direction and and habit-plane facets. Parallel moiré patterns are produced when the Ag precipitates and Cu matrix, with slight differences in atomic plane spacing, overlap. The elastic strains in the Ag precipitates have been detected by examining the moiré patterns. The measured elastic strains indicate that the misfit strain between the matrix and precipitate in the rod direction is more relaxed than that in the radius direction. A simple analysis using the elastic strains reveals that the elastic state in the semi-coherent Ag precipitates is hydrostatic. Precipitate growth along the ⟨011⟩ direction can be understood through the preferential relaxation of the misfit strain by the array of prismatic loops along the growth direction and the existence of the low-energy {111} habit planes.