The word krimi is used in Veda for different macroscopic & microscopic creatures. Right from bacteria, various insects like kita, patanga were nominated as krimi. Two types of krimi viz. Drishta (Visible/Macroscopic) & Adrishta (Invisible / Microscopic) were described in veda. These two categories encompases nearly all krimi (Microbes / pathogens). According to their origin & Habitat they were categorized as pranyashrayee & Anyasthanashrayee. Different sharirika, manasika & adhyatmic vyadhis were thought to be originated from these Krimis. These harmful & debilitates (Pushtinashaka) organisms were recognized by various names based on troubles/sufferings they produce. Sun & Agni (fire) were described as internal source of krimichikitsa. Today science also confirms this fact. That early morning ultraviolet light rays emanating from sun can be used for various krimijanya-vyadhis. Apart from this various treatment modalities by using various natural resources, vegetable drugs. mineral drugs, fumigation, cleansing (Marjan-prokshana) & hymns were described for krimi & diseases caused by them.