Background: Malnutrition is common in cancer and associated with greater treatment toxicity and poor clinical outcomes. Validated screening tools can identify individuals at risk; however, they are underutilized in clinical practice. It is also unclear how nutrition status is assessed and reported in oncology clinical trials. We analyzed nutrition assessment protocols in clinical trials published in major US oncology journals. Methods: Three researchers (YA, AA, VS) identified studies published in the Journal of Clinical Oncology, JAMA Oncology, and the New England Journal of Medicine under the “original reports”, “original articles”, or “’ research” categories, respectively (1/1/2022-12/31/2022). We selected studies that reported outcomes of systemic therapeutic interventions in any Phase clinical trial. This included chemotherapy, hormone therapy, and immunotherapy alone or combined with radiation therapy or surgical procedures. Systematic reviews, meta-analyses, commentaries, retrospective studies, and secondary analyses of pooled data from completed trials were excluded. Descriptive statistics summarized how malnutrition risk was assessed and nutrition data reported. Results: 521 articles were reviewed; 153 (29%) studies met eligibility criteria. Most were randomized trials (103/153, 67%) and Phase II or III (126/153, 82%). Malnutrition risk assessment was absent from all studies. Overall, 15/153 (10%) reported either baseline Body Mass Index or pre-treatment weight changes. These variables were included in the survival analysis of 5/15 studies. The primary cancer sites studied were breast (5/15), gynecologic (3/15), hematologic (3/15), multiple sites (2/15), prostate (1/15), and pancreatic (1/15). Conclusions: Most oncology clinical trials ignore and/or underreport nutrition status. Only 10% of the studies reported nutrition status data, and not all cancer sites were represented. There is a need to routinely assess nutrition status and (given the major prognostic value) investigate its potential uses for patient selection and stratification in clinical trials.