Inheritance and estimated genetic gains in a clonal test of hybrid Larch (Larix × eurolepis). Accepted Oct. 10, 1991. Scand. J. For. Res. 7: 355-365, 1992.A set of 101 clones structured in 14 full-sib families of hybrid Larch were compared on one test site at age 8. At that age, clone within family variation was an important part of the total variance for both vigour (15.2%) and stem form (26.7%). While the family component was negligible for vigour (3.0%), the latter was significant for stem straightness (13.9%). Variance components for total height seemed to be stabilized at age 8. Clonal heritabilities for both traits were high and genetic gains as high as 9.7% and 32.6% were expected for vigour and stem form respectively through direct selection. Nevertheless, severe unfavourable correlations between these traits have been detected. Simulation of index selection showed that still non-negligible gains might be expected on both vigour and stem form when constraints were put on stem form quality of selected clones to be similar to that of check seedlings. Interest of the clonal way for hybrid Larch propagation was discussed with respect to both genetic improvement and diversity.