Introduction. Cachexia is a syndrome characterized by the loss of musculoskeletal mass, with or without adipose mass, which cannot be reversed by nutritional support. In Chile, there are no data on cachexia in cancer patients that allows for decision making on better interdisciplinary management. In this study, the prevalence of cachexia in inpatient and outpatient cancer patients was investigated. Methods. An observational, descriptive, and cross-sectional study was carried out. Eighty-six inpatients and outpatients were evaluated. Cachexia was evaluated by applying the miniCASCO tool, its weight by bioimpedance, and inflammation by blood parameters. Comparisons and correlations were made considering as the threshold for statistical significance. Results. Forty patients met the inclusion criteria, 35% were men and 65% were women. In all, 27.5% of patients had cachexia secondary to cancer. Of the total number of patients with the syndrome, approximately 45.4% had mild cachexia, 36.3% had severe cachexia, and 18.1% had moderate cachexia. In addition, there was a significant positive correlation and moderately strong (r = 0.7209) match between the final scores and the stage of cancer. Conclusion. The prevalence of cachectic patients is reported for the first time through the application of the miniCASCO tool. A moderate positive match was detected between the final miniCASCO score and the stages of cancer patients. Finally, an early discovery of cachexia would allow therapeutic interventions aimed at improving the prognosis of cancer patients.