ABSTRACTHematological malignancies often lack defined risk factors and present with non‐specific symptoms, underscoring the urgent need for simple and reliable detection methods. To address this challenge, Hirotsu et al. innovated N‐NOSE, a novel, non‐invasive cancer screening test that utilizes the chemotaxis response of the nematode Caenorhabditis elegans to detect tumor‐related odors in urine. In this clinical study, we assessed the performance of N‐NOSE in patients with various hematological malignancies at diagnosis and during treatment. Urine samples were collected from 30 healthy individuals and 89 patients, including those with leukemia (n = 13), malignant lymphoma (n = 53), multiple myeloma (n = 15), primary AL amyloidosis (n = 3), Waldenström's macroglobulinemia (n = 2), myelodysplastic syndrome (n = 2), and blastic plasmacytoid dendritic cell neoplasm (n = 1). Based on the optimal cut‐off values in detecting hematological malignancies, N‐NOSE demonstrated high positivity rates in treatment‐naïve patients: leukemia and multiple myeloma were very high (over 90%), whereas malignant lymphoma was slightly lower than 80%. In the small subset of malignant lymphoma patients who tested N‐NOSE‐negative, confounding factors included steroid administration and hemodialysis. Importantly, no significant correlation emerged between N‐NOSE index values and baseline characteristics or comorbidities other than the presence of cancer. Moreover, in all 32 patients who achieved clinical response following chemotherapy, the N‐NOSE index declined, reflecting disease status. These findings highlight N‐NOSE's strong potential as a sensitive, non‐invasive screening tool for hematological malignancies—particularly multiple myeloma—and support its use in initial detection and monitoring of therapeutic response.