Abstract: A flashlamp-excited dye laser generating light pulses for therapy has a circulator which circulates a gain media through a dye cell. A controller coordinates operation by triggering flashlamps to excite the laser gain media while the circulator is circulating the gain media. This operation enables the effective generation of laser light pulses with a duration of at least one millisecond. The laser pulse is formed from many subpulses. If the flow velocity of dye solution is great enough such that the new solution enters the resonant cavity before the solutions in the cavity are substantially spent, subsequent subpulses are not quenched, enabling the generation of ultra-long effective pulses with high fluences. Specifically, longer effective pulses of up to 50 msec are attainable with energies of up to 50 Joules. These energies enable reasonable spot sizes, which makes the invention relevant to cutaneous as well as deep tissue therapy, for example.