The present invention relates to a method for diagnosing renal cell carcinoma (RCC) in a subject comprising the steps of: i) measuring the expression level of soluble SEMA7A in a fluid sample; ii) comparing the expression measured at step i) with its predetermined reference value, and iii) concluding that the subject suffers from RCC when the expression level of SEMA7A is higher than its predetermined reference value. Inventors found that SEMA7A was detected in all patients despite the disease ontogeny. SEMA7A levels were significantly reduced in patients one month after nephrectomy, and almost inexistent in healthy donors. This reinforces the specific correlation of SEMA7A to renal cell carcinoma. More importantly, SEMA7A was detected in all grades IV of RCC at similar levels, suggesting that it could be an early stage biomarker. Taken altogether, these data define SEMA7A as an early circulating biomarker of renal cell carcinoma, allowing early diagnosis in a non-invasive manner.