Minerals and vitamins are essential nutrients in poultry diets that play a crucial role in growth, egg production, reproduction, and overall health. Deficiencies in these nutrients can lead to serious diseases in chicks and layers, affecting productivity and sometimes causing mortality. Five common mineral and vitamin deficiency diseases in poultry are rickets, perosis, goitre, vitamin A deficiency, and vitamin D deficiency, each with distinct symptoms. Rickets is primarily caused by a deficiency of calcium, phosphorus, or vitamin D in growing chicks. It affects the proper mineralization of bones, leading to weak, soft, and deformed skeletal structures. Chicks suffering from rickets often show bowed legs, enlarged joints, thickened beaks, and stunted growth. In severe cases, the sternum may be bent or twisted, and chicks may have difficulty standing or walking. Poor eggshell quality in later stages can also occur if laying birds experience prolonged calcium deficiency. For example, a flock of broiler chicks fed with a diet low in vitamin D showed severe leg deformities and delayed weight gain, clearly indicating rickets. Perosis, also known as slipped tendon, occurs due to manganese deficiency, sometimes aggravated by a lack of biotin or choline.