In the title mol-ecule, C22H21N3, the isoquinoline ring is almost planar [maximum deviation = 0.046 (1) Å] and makes dihedral angles of 52.01 (4) and 14.61 (4)° with the pyrazole and phenyl rings, respectively. The phenyl ring and the pyrazole ring are twisted by 44.20 (6)° with respect to each other. The terminal C atoms of both of the ethyl groups attached to the pyrazole ring are disordered over two sites with occupancy ratios of 0.164 (7):0.836 (7) and 0.447 (16):0.553 (16). A weak intra-molecular C - H⋯N contact may influence the mol-ecular conformation. The crystal structure is stabilized by C - H⋯π contacts involving the phenyl and pyrazole rings, and by π-π stacking inter-actions involving the pyridine and benzene rings [centroid-centroid distance = 3.5972 (10) Å].