Objective: To analyse growth and development of girls with slowly progressive idiopathic precocious or early puberty. Design: Long-term open clinical study. Setting: Department of Obstetrics and Gynaecology, Second Faculty of Medicine, Charles University, Prague. Methods: In 20 untreated girls with slowly progressive puberty starting at 6–9 years neurogenic aetiology was excluded. During follow-up period 4.7 ± 2.2 (2–8,5) years (mean ± SD; range), sexual development (Tanner criteria), age at menarche, menstrual cycle and auxological parameters were evaluated. Results: 13 girls reached menarche at 11.1 ± 0.9 years (3.7 ± 1.1 years after the onset of puberty), earlier than in their mothers (12.9 ± 1.1 years) and Czech standards (P < 0.05). Menstrual cycle 28 (24–29) days was regular in all 6 girls with gynaecological age > 2 years. In one girl microprolactinoma was diagnosed, therapy with bromocryptine started at the age 14.7 years (3.5 years after menarche). At the onset of follow-up, bone age (TW20) advancement was 1.8 ± 1.4 years above the chronologic age. Initial prediction of final height (graphic method) was 162.3 ± 5.5 cm vs final prediction 163.7 ± 5.1 cm. Final height 162.2 ± 5.7 cm achieved 7 girls vs target height 163.6 ± 5.2 cm (NS). Conclusion: In untreated girls, menarche occurred later after the first signs of puberty than in normal population, menstrual cycle was regular. Height potential was preserved, final height corresponded with their target height. Not all girls with early and slowly progressive puberty should be treated. Therapy is necessary in organic aetiology, rapid progressive precocious puberty and impaired growth prognosis.

        Key words: precocious puberty, untreated girls, growth, sexual development, final height