Because CML is slow-growing cancer, many people do not have symptoms when they are first diagnosed.

In fact, up to 40 to 50 percent of patients do not have any symptoms at all, and they receive their diagnosis after routine blood work detects an abnormality.

CML may cause symptoms as it progresses with time, however. Given this situation, the list of "most common symptoms" can be described as follows:
__No symptoms (up to 50 percent of people at diagnosis)
__Extreme tiredness or fatigue
__Weakness
__Fever
__Night sweats
__Unexplained weight loss
__Pain or fullness in the upper left abdomen, beneath the ribs.

The last symptom in the list is due to an enlarged spleen, also called splenomegaly, which is present in 46 to 76 percent of those with CML. Such enlargement of the spleen can result in less space for the other organs in the area, like the stomach, which may contribute to a sense of becoming full early when eating a meal.

The weakness and fatigue that some people with CML experience can develop from a number of different sources. One source of weakness and fatigue is anemia, which means the body does not have enough healthy red blood cells that carry oxygen to the tissues. Anemia can also make you feel like you won’t be able to exert yourself or use your muscles as vigorously as usual.