The present study aimed to highlight the new or lesser known medicinal uses of plant bioresource along with validation of traditional knowledge that is widely used by the tribal communities to cure four common ailments in Lahaul-Spiti region of western Himalaya. The study area inhabited by Lahaulas and Bodhs (also called as Bhotias), is situated in the cold arid zone of the state of Himachal Pradesh (HP), India. During the ethnobotanical explorations (2002-2006), observations on the most common ailments like rheumatism, stomach problems, liver and sexual disorders among the natives of Lahaul-Spiti were recorded. Due to strong belief in traditional system of medicine, people still prefer to use herbal medicines prescribed by local healers. A total 58 plant species belonging to 45 genera and 24 families have been reported from the study area to cure these diseases. Maximum use of plants is reported to cure stomach disorders (29) followed by rheumatism (18), liver problems (15) and sexual ailments (9). Among plant parts used, leaves were found used in maximum herbal preparations (20) following flowers (12) and roots (11) respectively. Most of these formulations were prescribed in powder form, whereas juice and decoction forms were also used. Plants having more than one therapeutic use were represented with 24 species, however 34 species were reported to be used against single specific ailment. Validation of observations revealed 38 lesser known or new herbal preparations from 34 plant species, where 15 species were used to cure stomach disorders, 7 for rheumatism, 10 for liver disorders and 6 for sexual problems. Mode of preparation, administration and dosage are discussed along with the family and local names of plants and plant parts used.