Abstract: A method for testing at least one nozzle of a multi-jet print head of an inkjet printer including a plurality of nozzles (4), at least one 1st and one 2nd deviation electrode (14a, 14b) for each jet, method in which: at least one jet is formed using the nozzle (9), at a drop formation frequency, an estimate is made of: a cutoff frequency (Fc) of at least this jet, by variation of the jet formation frequency, at a constant jet velocity, or, at constant formation frequency of the drops from at least this jet, by variation of the jet velocity, the velocity at which the cutoff frequency (Fc) is equal to the formation frequency; this cutoff frequency (Fc) or this velocity is compared with a reference value and the functional or non-functional state of at least the nozzle is deduced.