This study aimed to compare the diagnostic effectiveness of serum sialic acid (SA) and carcinoembryonic antigen (CEA) as tumor markers in cancer patients. The research was conducted at the Shaikh Zayed Medical Complex in Lahore, Pakistan, involving 153 cancer patients (130 carcinomas, 17 hematological malignancies, and 6 sarcomas) and 50 matched controls. Sialic acid was measured using a colorimetric procedure, while CEA was measured by enzyme immunoassay. The results showed that both SA and CEA levels were significantly higher in cancer patients compared to controls (p<0.05). However, sialic acid was found to be more sensitive (p<0.05) than CEA in detecting cancer. Specifically, sialic acid levels were significantly higher in all cancer groups, including carcinomas, hematological malignancies, and sarcomas. In contrast, CEA levels were significantly higher only in hematological malignancies and sarcoma patients. The study concluded that sialic acid is a better diagnostic marker than CEA for cancer patients, particularly in detecting carcinomas and hematological malignancies. This finding suggests that sialic acid could be a valuable tool for early cancer detection and management.This study aimed to compare the diagnostic effectiveness of serum sialic acid (SA) and carcinoembryonic antigen (CEA) as tumor markers in cancer patients. The research was conducted at the Shaikh Zayed Medical Complex in Lahore, Pakistan, involving 153 cancer patients (130 carcinomas, 17 hematological malignancies, and 6 sarcomas) and 50 matched controls. Sialic acid was measured using a colorimetric procedure, while CEA was measured by enzyme immunoassay. The results showed that both SA and CEA levels were significantly higher in cancer patients compared to controls (p<0.05). However, sialic acid was found to be more sensitive (p<0.05) than CEA in detecting cancer. Specifically, sialic acid levels were significantly higher in all cancer groups, including carcinomas, hematological malignancies, and sarcomas. In contrast, CEA levels were significantly higher only in hematological malignancies and sarcoma patients. The study concluded that sialic acid is a better diagnostic marker than CEA for cancer patients, particularly in detecting carcinomas and hematological malignancies. This finding suggests that sialic acid could be a valuable tool for early cancer detection and management.