Fatal Drug Crimes Act of 1988 - Amends the Controlled Substances Act to provide that in the case of a violation involving any controlled substance in schedule I or II, other than marijuana, if death results from the use of such substance, such person shall be subject to the death penalty or life imprisonment.

Sets forth procedures for the imposition of the death penalty. Prohibits sentencing to death any person under 18 years of age at the time of the offense.

Sets forth mitigating factors to be considered by the jury or the court in determining whether a sentence of death is justified. Includes as aggravating factors to be considered: (1) previous convictions for Controlled Substances Act violations; and (2) the creation of a grave risk to persons other than the victim.

Requires the Government, for such offense, to serve notice upon the defendant a reasonable time before trial or acceptance of a plea, disclosing that it intends to seek the death penalty and the aggravating factors upon which it will rely.

Requires a separate sentencing hearing before a jury, or the court upon motion by the defendant, when the defendant is found guilty.

Allows the defendant and the Government to present any information relevant to sentencing, without regard to the rules of evidence, but permits information to be excluded where its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading of the jury.

Requires the court to instruct the jury not to consider the race, color, national origin, or sex of the defendant in its consideration of the sentence. Requires each juror to return a signed certificate stating that race, color, national origin, creed, or sex of the defendant was not involved in such juror's decision.

Directs the court: (1) upon a finding that the death sentence is justified, to sentence the defendant to death; and (2) upon a finding that no required aggravating factor exists or that such sentence is not justified, to impose a sentence of life imprisonment.

Establishes procedures for appeal from a death sentence. Requires the Court of Appeals, upon consideration of the record and the information and procedures of the sentencing hearing, to affirm the decision if: (1) the sentence was not imposed under the influence of passion, prejudice, or arbitrariness; and (2) the information supports the finding of aggravating factors. Requires the court to provide a written explanation of its determination.

Requires a death sentence to be implemented in the manner prescribed by the State in which the sentence is imposed or, if such State's laws do not provide for a death sentence, as prescribed by another State as designated by the court. Prohibits the death sentence from being carried out upon a person who lacks the mental capacity to understand the death penalty and why it was imposed or upon a woman while she is pregnant.