I am learning cell culture and while reading about counting cells and viability percentage, I am confused. Some recommend use of Hemocytometer and others tell about MTT. Hemocytometer is highly preferable, yet it is not devoid of human error. On the other hand, MTT is not clear of drawbacks. It is not always reliable as it can not always differentiate between the dead and alive cells and there are many factors needed to consider before performing the assay.