Blood in the semen is called hematospermia. It is usually a self-limited condition that tends to be benign, but in older patients, it may rarely be associated with malignancy. Most commonly it is associated with an inflammatory condition of the prostate (such as prostatitis) or the seminal vesicles. Blood clots in the urine however may be indicative of something not related to the ejaculation, but rather in the bladder and should be further evaluated. If the blood in the semen becomes persistent, further evaluation with a urologist would be advised.