Costello faciocutaneoskeletal syndrome is a rare disorder until now unknown, probably heterogenous etiology with mental retardation and increased risk for solid malignant tumors since childhood. Face is coarse with hypertelorism, wide short nose with anteverted nostrils, full cheeks with prominent corpus adiposum buccae, macrostomy with thick lips, open mouth, large auricles with upstanding lobules. Skin is loose, redundant, lipodystrophic, velvet, hyperelastic, dark with hirsutism, wrinkled with deep palmar and plantar creases, acanthosis nigricans on the neck and axillas, since infancy can occur dark verucas and periorifitial papillomata, hair is rich, curly with alopetic lesions, nails are thin and deep set. Skeletal anomalies include short stature, short neck, hyperexcursible broad fingers with broad distal phalanges, decreased range of elbow motion, pedes plano/calcaneovalgi. Mental retardation is mild due to sociable, humorous behavior. Letalita is increased in infancy due to cardiac arrhythmia or metabolic disorder of glycids, later due to malignant tumors and cardiomyopathy. Etiology and pathogenesis of this syndrome are still unknown, recurrence risk is low and supports hypothesis of new dominantmicrodeletion.Author reports two patients with Costello syndrome, who were followed up since the birth.

        Key words: faciocutaneoskeletal anomalies, elastolysis, mental retardation, humorous behavior, increased risk of solid tumor manifestation, clinical and genetic prognosis