Inclusion Criteria:

* Participants must be suspected to have previously untreated acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Participants with AML cannot have a history of previously treated myeloproliferative neoplasms (MPN) or MDS.
* Participants must be \>= 18 years of age.
* Participants must not have received prior anti-cancer therapy for AML or MDS.

* Note: Hydroxyurea to control the white blood cell count (WBC) is allowed.
* Note: Prior erythroid stimulating agent (ESA) is not considered prior therapy for the purposes of eligibility. Participants must not be currently receiving any cytarabine-containing therapy other than up to 1 g/m\^2 of cytarabine, which is allowed for urgent cytoreduction.
* Participants are allowed prior use of hydroxyurea, all-trans retinoic acid (ATRA), BCR-ABL directed tyrosine kinase inhibitor, erythropoiesis-stimulating agent, thrombopoietin receptor agonist and lenalidomide, with a maximum limit of 1 month of exposure.

* Note: Participants receiving hydroxyurea prior to treatment substudy or TAP assignment must agree to discontinue hydroxyurea within 24 hours before beginning substudy or TAP treatment.
* Participants must not have a prior or concurrent malignancy that requires concurrent anti-cancer therapy

* Note: active hormonal therapy is allowed
* Participants must have a Zubrod Performance Status evaluation within 28 days prior to registration.
* Participants must agree to have translational medicine specimens submitted.
* Participants must be offered the opportunity to participate in specimen banking.

* Note: Specimens must be collected and submitted following the initial paper-based process and subsequently via the Precision Medicine Specimen Tracking Forms in Medidata Rave instance for the MyeloMATCH MSRP.
* Participants must be informed of the investigational nature of this study and must sign and give informed consent in accordance with institutional and federal guidelines.

* Note: As a part of the Oncology Patient Enrollment Network (OPEN) registration process the treating institution's identity is provided in order to ensure that the current (within 365 days) date of institutional review board approval for this study has been entered in the system.
* The master screening and reassessment protocol (MSRP) should only be used in sites where the relevant AML treatment substudies are open or if the site is willing to follow the MSRP Tier Advancement Pathway (TAP) for patients in the event that the site does not have the relevant study open and transfer to another site that does have the study open. For example, if a site does not have a myeloMATCH Tier 1 study for older AML open for enrollment, such older AML patients should only be consented for the MSRP if the site is willing to treat the patient with standard of care on TAP or is willing to transfer the patient to a center with a study open that the patient would otherwise match to.