Short answer. Generally no, not for lesion alone. Under Article 1099, a partition made by the testator in the will cannot be attacked simply because your share is smaller than another heir's. The two exceptions are if your legitime was prejudiced, or if the testator's own intent was different from what the will says.
What the law says
The partition made by the testator cannot be impugned on the ground of lesion, except when the legitime of the compulsory heirs is thereby prejudiced, or when it appears or may reasonably be presumed, that the intention of the testator was otherwise.
Civil Code, Article 1099 — Partition by the Testator. Read the full provision →
What lesion means and why the rule exists
Lesion is a complaint that one party received significantly less than fair value in a transaction. In ordinary contracts, serious lesion can be a ground to rescind. But a testator dividing an estate has a different status — the law gives them wide latitude to favor some heirs over others, assign specific properties, and arrange things according to their own judgment. Article 1099 respects that freedom: the partition made by the testator cannot be impugned on the ground of lesion. Receiving a smaller house than your sibling, or a plot worth less, does not by itself void the testator's plan.
When you can challenge it: the legitime exception
The first and most important exception is when the partition prejudices your legitime. The legitime is the minimum share that the law reserves for compulsory heirs — children, surviving spouse, and in some cases parents — which the testator cannot take away by will. If the testator's own partition left you with less than your legal minimum, that portion of the partition can be challenged and corrected. The excess, beyond the free portion, must be restored to make up your reserved share.
When you can challenge it: the intent exception
The second exception applies when it appears, or may reasonably be presumed, that the testator's actual intention was different from what the partition produces. This is narrower than it sounds. A bare argument that a parent surely meant to treat all children equally is not enough. The intent must be evident from the will itself, other provisions in the document, or surrounding circumstances that point clearly to a different plan than the one the partition created.
What to do next
Start by identifying your exact legitime under the rules on succession and comparing it to what the partition actually gives you. If your share falls short of that legal minimum, you have a concrete basis to act. If your legitime is intact but you simply received less than others, examine the will carefully for any language or arrangement that suggests the testator intended otherwise. These are fact-specific questions; have a lawyer review the will and the asset values before deciding whether to pursue a challenge.