The effectiveness of an abamectin formulation (VertimecR EC) for the control of the carrot cyst nematode Heterodera carotae Jones was investigated in an in vitro hatching test. Abamectin is a mixture of macrocyclic lactones produced by the actinomycete Sptreptomyces avermitilis especially known for its acaricidal and insecticidal activities. Cysts of the nematode were subjected for different exposure times (24, 48, 96, 192, 384 hours) to different concentrations of an aqueous solution of the abamectin formulation (0, 1.125, 2.25, 4.5, 9.0, 18.0 and 36 g/ml). Cysts were extracted by the Fenwich can. Batches of 50cysts of similar sizewere placed on 2 cm diam sieves (215 m aperture).Each sieve was put in a 3.5 cm diam Petri dish, and all dishes were arranged according to a complete randomized block design. For each treatment (exposure time x concentration) three replications were considered. Carrot root leachate was used as natural hatching agent. Three ml ofthe carrot root leachate were added to each batch of cysts, which were then incubated in a growth cabinet at 20 Ѓ} 2 °C. Emerged juveniles were counted weekly renewingthe hatching agent at the same time, over a 10week period. At the end of the hatching test cysts were crushed and unhatched eggs and juveniles were counted. Numbers of second stage juveniles emerging weekly were expressed as cumulative percentages of the total egg content of the cysts. For each exposure time the untreated cysts (0 concentration) were used as control. From percentages hatch the mortality for each treatment was assessed according to the formula% Mortality = 100 - % hatched juveniles (J2) where% hatched J2 = (N° hatched J2 in treatment/ N° hatched J2 in control)*100 Percentage hatch data were statistically analyzed after transformation in arcsen root square values by ANOVA and the effects of abamectin concentrations, exposure times and their interactions were examined by 7 x 5 factorial design (Table1). On the base of total emergence data, abamectin concentrations needed to obtain 50, 60, 70, 80, 90 and 99.9% nematode mortality were also calculated using probit analysis (Software PlotIT V.3.2) (Table 2). Results clearly demonstrate the efficacy of abamectinat all tested applied concentrations with an increaseof nematode mortality by the increase of abamectin concentration. Moreover, efficacy increased by increasing exposure time at each concentration. Aknowledgement: The research was undertaken within the framework of the bilateral project nr. 15.820.18.05.07/It between the National Research Council (CNR-Italy) and the Academy of Science of Moldova nr. 15.817.02.12F.